I suspect a big part of what's different under systems used at other developed countries that are significantly cheaper is that they do exactly what the parent proposed.
Another would be that you don't necessarily have the country's largest industry association behaving like a medieval guild and choking off access to the profession in order to deliberately drive up costs.
This * 100. I made many comments on HN about this because I know quite a bit about both the US system and the one that is NOT. My late data is a doctor. I went to med school in a SE Asian country (dropped out after 3rd year because studying medicine is not my thing; I hate rote learning and memorizing a lot of things like 200+ bone names on human body). I am married to a current medical resident (in the US) who graduated from the same medical school in SE Asia.
Both my wife and I were very much surprised at how much it costs and how many more hurdles one has to overcome to become a doctor in the US. Sure, we would like our brain surgeons and orthopedics to be trained extremely well. But we really don't need 8 years of schooling, 3-8 years of residency+fellowship training on top of many, many exams (Step 1, 2 CK, 2 CS, 3, state licenses) to become a competent doctor. After all, the doctors in the US have to follow the code/guidance set mostly by insurance companies to avoid being sued (meaning, they don't have a lot of leeway to use their intelligence in treating patients; they simply try to not get sued, so they would tell you to get tested on everything possible in order to avoid malpractice lawsuits later, which actually do happen much much higher than in other countries that I know of). The trust between doctors and patients is very, how do I say it, much impersonal and money based.
AMA, test prep companies (Kaplan, UWorld, AMBOSS), residency programs and everyone in the field are (either intentionally or unintentionally) making the bar to entry as high as possible (higher than necessary) to keep the number of doctors available low (my sister who lives in Rochester, NY cannot book a physician for annual check-up until May). India produces plenty of qualified doctors. So does my country (I'd say my country has produced so many doctors for Singapore, Australia and the US; they, like my wife, came to the US and AUS because they can make so much more money here). The field of medicine in the US is paved with money and has become very transactional (I pay you a lot, you'd better treat me and not mess up or else I'll sue you) and impersonal.
Up to a point I agree with you. I worked with an Indian guy that had been pushed into medicine by his parents and had moved to the US (with an arranged marriage) to escape their influence and quit being a doctor since he really disliked medicine. He had 2 years of secondary education then a residency. Every time I had a medical problem he was able to quickly and correctly diagnose it and tell me what I needed to do. He obviously wasn't able to prescribe anything to me here in the States, but when I went to my regular doctor they arrived at the same conclusion he had. Heck most PA's and NP's here have more medical education than him, but he could get the bulk of diagnoses correct. Why do we need so many physicians struggling under crippling debt to diagnose arm fractures, ear infections, and ring worm? Let the more exotic things trickle up to specialists instead.
Another would be that you don't necessarily have the country's largest industry association behaving like a medieval guild and choking off access to the profession in order to deliberately drive up costs.