This could be an opportunity for me to learn something new...
I thought the American Medical Association were the ones who artificially constrain the supply of physicians. Is that not true, or is the AMA constraint transitively related to the Medicare caps in some manner?
Which I think itself is a bit of a red herring. Medicare subsidized residency slots are not the only way training doctors could be funded, and largely an artifact of our billing procedures and criteria.
It is just one aspect of how incredibly constrained the supply of healthcare is in the US. Medications that are over the counter in many countries requires someone with 12 years of training.