"Anyone who says Onkelos is just a translation, is mistaken."
(excerpt from an approbation of Sefer Nefesh HaGer, a supercommentary on Targum Onkelos)
The passuk says in this week’s Parsha, Parshas Mishpatim:
(יט) אִם־יָק֞וּם וְהִתְהַלֵּ֥ךְ בַּח֛וּץ עַל־מִשְׁעַנְתּ֖וֹ וְנִקָּ֣ה הַמַּכֶּ֑ה רַ֥ק שִׁבְתּ֛וֹ יִתֵּ֖ן וְרַפֹּ֥א יְרַפֵּֽא׃ {ס}
(19) If that victim then gets up and walks outdoors upon a staff, the assailant shall go unpunished—and he shall surely cure him.
Onkelos renders the passuk as follows:
(יט) אִם יְקוּם וִיהַלִיךְ בְּבָרָא עַל בּוּרְיֵהּ וִיהֵי זַכָּאָה מָחְיָא לְחוֹד בּוּטְלָנֵהּ יִתֵּן וַאֲגַר אַסְיָא יְשַׁלֵם:
(19) If that victim then gets up and walks outdoors on his own power, the one who struck him shall be acquitted. Still he must pay for his loss of work, and he must pay the doctor’s fee.
We see that Onkelos renders the last clause significantly different from the simple reading of the passuk; the simple reading makes no mention of a doctor being the care provider specifically, nor is there any mention of monetary compensation, yet Onkelos incorporates both of those into the passuk.
Although Onkelos does sometimes elaborate in his rendering of a passuk when the simple reading is particularly terse and not readily understood by the simple reading, however in this instance it seems like Onkelos is straying unusually far from the simple reading of the passuk?
And perhaps a more educated and pointed question which relates specifically to pointedly this passuk can be asked: In explaining the double verbiage of the clause “v’rapo yerapei”, the Gemara in Bava Kamma 85a expounds this very clause:
רִיפּוּי דִּתְנָא בֵּיהּ קָרָא – לְמָה לִי?
מִיבְּעֵי לֵיהּ לְכִדְתָנָא דְּבֵי רַבִּי יִשְׁמָעֵאל – דְּתַנְיָא, דְּבֵי רַבִּי יִשְׁמָעֵאל אוֹמֵר: ״וְרַפֹּא יְרַפֵּא״ – מִכָּאן שֶׁנִּיתַּן רְשׁוּת לָרוֹפֵא לְרַפּאוֹת.
The Gemara asks: How do I account for, the fact that the verse repeated the obligation to pay medical costs?
The Gemara answers: It is necessary for that which the school of Rabbi Yishmael taught. As it is taught in a baraita that the school of Rabbi Yishmael says: When the verse states: “And shall cause him to be thoroughly healed [verappo yerappe]” (Exodus 21:19), it is derived from here that permission is granted to a doctor to heal, and it is not considered to be an intervention counter to the will of God.
In short, Onkelos on this clause is veering from the simple reading of the passuk and shying away from plugging in the Talmudical exegesis too.
What then is Onkelos getting at here?
After the aforementioned Gemara where the double-verbiage v’rapo yerapei is expounded, the Gemara continues on the topic of the assailant's responsibility to heal the victim. The Gemara says:
וְאִי אֲמַר לֵיהּ: ״אָסְיָיךְ אֲנָא״, אֲמַר לֵיהּ: ״דָּמֵית עֲלַי כְּאַרְיָא אָרְבָא״. וְאִי אֲמַר לֵיהּ: ״מַיְיתִינָא אָסְיָא דְּמַגָּן (בְּמַגָּן)״, אֲמַר לֵיהּ: ״אָסְיָא דְּמַגָּן (בְּמַגָּן) – מַגָּן שָׁוֵה״. וְאִי אָמַר: ״מַיְיתִינָא לָךְ אָסְיָא רַחִיקָא״, אֲמַר לֵיהּ: ״אָסְיָא רַחִיקָא – עֵינָא עָוַירא״. וְאִי אֲמַר לֵיהּ הַיְאךְ: ״הַב לִי לְדִידִי, וַאֲנָא מַסֵּינָא נַפְשַׁאי״, אֲמַר לֵיהּ: ״פָּשְׁעַתְּ בְּנַפְשָׁךְ וְשָׁקְלַתְּ מִינַּאי טְפֵי״. וְאִי אֲמַר לֵיהּ: ״קוּץ לִי מִקָּץ״, אֲמַר לֵיהּ: ״כׇּל שֶׁכֵּן דְּפָשְׁעַתְּ בְּנַפְשָׁךְ, וְקָרוּ לִי: ״שׁוֹר הַמַּזִּיק״.
The Or HaTargum, a supercommentary on Onkelos, says that Onkelos’ addition of “the doctor’s fee” is alluding to the first teaching of the Gemara, that the victim may deny the assailant’s cannot request to do the treatment, and may request a third-party doctor to be brought in.

(ג) ישלם שכר הרופא. כלומר, אבל הוא לא ירפא אותו בעצמו, כדמשמע הלשון "ירפא", דאפילו אם היה המכה רופא לא ירפא אותו, כדאיתא בגמרא (ב"ק סוף פה.) דאמר ליה הנחבל דדמית עלי לארי, שחבלת בי ואתה רוצה לרפאני, מתיירא אני שתזיק אותי יותר, הכי איתא התם:
The Nesina LaGer, another supercommentary on Onkelos, zeroes in on another part of Onkelos’ rendering, “the doctor's fee” as alluding to the Gemara’s subsequent teaching that the victim may deny deny the assailant’s request to have the job done for free, and may demand a doctor to be hired to do the job.

It comes out that in just two words Onkloes is alluding to a flowing Gemara in Bava Kamma, one line after the other!
However, the question can still be asked, why is Onkelos explaining the passuk from the angle of this Gemara in Bava Kamma, and not according to the simple explanation or the drasha which is more on the nose?
First we need to understand the entire M.O. of Onkelos. The Meforshei Onkelos say that Onkelos’ agenda in his translation-commentary is not to necessarily explain the exact words of the passuk, but instead to bring out the overarching idea (inyan) of the passuk. Sometimes word for word literal translation into Aramaic is sufficient, sometimes the drasha of Chazal comes in to clarify it, and other times, like here, neither one captures the overarching idea, and Onkelos finds another way to get to that destination.
In this case in particular, it is the subsequent Gemara (which ironically comes directly after where the Gemara expounds the words of the passuk), which he chooses to represent the idea of the passuk.
How does Onkelos see idea of hiring a doctor the overarching theme of the passuk “and he shall surely heal him?”
Perhaps the explanation is that, through the double-verbiage, the passuk is emphasizing that the intended end result is for the victim’s healing to be seen to full fruition.
When either of these two conditions are in play, that is if the assailant himself is administering the treatment or it is being done for free, the result of full recovery is at risk.
According to this explanation, the aforementioned Gemara is a great pick for representing the intention behind the words “he shall surely be healed”, right in line with Onkelos’ agenda.
[To further this idea, the Poskim discuss whether a doctor is even allowed to reduce a fee* or waive a fee for their services. Like we mentioned, when a doctor isn’t getting his “monetary motivation” it can result in him doing a sub-par job and endanger the patient. See Yam Shel Shlomo Siman 10 and Shevus Yaakov 86.]
In a similar vein the Gemara in Kiddushin says:
רַבִּי יְהוּדָה אוֹמֵר מִשְּׁמוֹ...טוֹב שֶׁבָּרוֹפְאִים – לְגֵיהִנָּם,
Rabbi Yehuda says in Abba Gurya’s name...the best of doctors is to Gehenna.
טוב שברופאים לגיהנם - אינו ירא מן החולי ומאכלו מאכל בריאים ואינו משבר לבו למקום ופעמים שהורג נפשות ויש בידו לרפאות העני ואינו מרפא:
'The best of doctors is to gehenna' - They do not fear disease. They eat the food of the healthy, and they do not act humbly before God. Sometimes they kill, and sometimes they are able to heal a poor person but do not do so.
Although the Gemara seems to take aim at this group of doctors, in light of what we are saying, it is a “backhanded compliment” since these doctors hold themselves to providing a consistently high standard of care which they know can only be achieved if they are paid commensurate for the services they are offering.
While not all of us are doctors, we can all take an important lesson from here. Part of how Hashem made us was to need to be rewarded in order for us to produce quality work. It isn’t something to be ashamed of to demand that your value is recognized and compensated accordingly.
"If you know what you're worth, then go out and get what you're worth!"
(Rocky)
Good Shabbos!
Further Reading and Sources
(ד) ורפא ירפא. כְּתַרְגּוּמוֹ – יְשַׁלֵּם שְׂכַר הָרוֹפֵא:
(4) ורפא ירפא — Translate it as the Targum does: he shall pay the physician’s fee.

However, this klal doesn't seem to be agreed upon by all meforshim, see Ohr HaChama to Rashi in the previous passuk:
(ב) ונפל למשכב. כְּתַרְגּוּמוֹ וְיִפֵּל לְבוּטְלָן – לְחֹלִי שֶׁמְּבַטְּלוֹ מִמְּלַאכְתּוֹ:
(2) ונפל למשכב BUT KEEPETH HIS BED — The meaning is as the Targum gives it: ויפל לבוטלן “and he falls into inactivity”, i. e. he falls into an illness that prevents him from working.
(יז) אָמַר לוֹ הַנִּזָּק פְּסֹק עִמִּי וְתֵן עַל יָדִי וַאֲנִי אֲרַפֵּא אֶת עַצְמִי אֵין שׁוֹמְעִין לוֹ שֶׁהֲרֵי אוֹמֵר לוֹ שֶׁמָּא לֹא תְּרַפֵּא עַצְמְךָ וְאֶחֱזַק אֲנִי כְּמַזִּיק אֶלָּא נוֹתֵן לוֹ דְּבַר יוֹם בְּיוֹמוֹ. אוֹ פּוֹסֵק עַל הַכּל וְנוֹתֵן דְּמֵי הָרִפּוּי עַל יְדֵי בֵּית דִּין:
(יח) אָמַר לוֹ הַמַּזִּיק אֲנִי אֲרַפֵּא אוֹתְךָ אוֹ יֵשׁ לִי רוֹפֵא שֶׁמְּרַפֵּא בְּחִנָּם אֵין שׁוֹמְעִין לוֹ אֶלָּא מֵבִיא רוֹפֵא אֻמָּן וּמְרַפְּאֵהוּ בְּשָׂכָר:
(17) If the person who suffered the injury says: "Assess my injury and give me the money. I will heal myself," his request is not accepted. For the person who caused the injury can say: "Perhaps you will not be successful in healing yourself, and I will be viewed as responsible for the injury." Instead, he must pay his medical expenses day by day, or pay an assessment for the entire amount and give the money for his medical expenses to the court on his behalf.
(18) If the person who caused the injury says: "I will heal you," or he says: "I have a physician who will heal you without charge," his words are not heeded. Instead, he is required to bring a professional physician who charges for healing him.
(א) אמר לו המזיק וכו'. בפ' החובל אמרו עוד ואי א"ל מייתינא לאסיא דחיקא א"ל אסיא דחיקא עינא עוירא ע"כ. ומדברי הטור נראה דגורס אסיא רחיקא ר"ל ממקום רחוק וכן היא גירסת הרא"ש והכוונה לומר רופא שמוזיל גביה ורבינו לא הזכיר מזה כלל:
וצריך לשכור לו רופא ואם יאמר החובל אני ארפאך או יש לי רופא שירפאך בחנם אין שומעין לו שיאמר הנחבל כשאין הרופא מצפה לקיבול שכר אינו מעיין כל כך בענין החולי ואם יאמר אני אביא רופא ממקום רחוק שיקח שכר מועט יכול הנחבל לומר לו הרופא שהוא במקומי הוא מדקדק יותר שלא יפסיד המחאתו ואם יאמר הנחבל תן לי שכר הרופא וארפא את עצמי יכול החובל לומר לו שמא לא תרפא עצמך יפה ויקראו אותי מזיק לעולם.