The AMA is only a private professional association. They have some political influence but no regulatory authority. Medical schools have to be accredited so that's one limiting factor. But the real bottleneck today is more lack of slots in graduate medical education (residency) programs. Every year there are some students who graduate with an MD but can't practice medicine because they don't get matched to a residency program. To expand the supply we have to start there.

https://www.ama-assn.org/education/gme-funding/save-graduate...