Compare the mastery of surgery to the mastery of Rachmaninoff.
Now on a daily basis, no matter how tired you are, or what time it is, play his Piano Concerto no. 3, perfectly.
There is only a small percentage of a small percentage who could do that.
Also, surgical training doesn't "really" begin after med school, it starts in undergrad, where you learn the basics of the human body, biology, and chemistry. Once you've gotten enough of a grasp of the topics to perform marginally well in medical school you show off the speed at which you can recall and apply this knowledge on the MCAT. If you show you can do that you are granted entrance into medical school, there you cram vast amounts of information into your memory, and then you again show your knowledge. If you can perform well enough in classes, research and on Step 1 and Step II, then you again apply to numerous residencies, surgical residencies have incredibly high standards, and 14 hours every single day in that field could break even the most courageous spirit. That's not even to mention that any good surgeon practices their technique while at home too. Most people wouldn't be able to do it, even in a hypothetical egalitarian society, its honestly just that difficult.