I'm very glad you pointed that out; I mean, jparks makes the same claim you make - that salaries aren't the problem - and doesn't address the artificial restriction of doctors at all. In other words, he fails to refute the "AMA isn't a cartel" claim. If you prevent the AMA from artificially restricting doctor supply, the overall cost of health care drops significantly, and the health of the population increases considerably.
As a consequence of the overwhelmingly positive benefit of lifting the artificial supply of MD (or DO), doctor salaries will naturally drop, as necessitated by economics.
I think you're focusing a bit too hard on this. If we broke the AMA cartel, prices would not magically fall to be in line with other developed nations. The AMA cartel is certainly a factor, and not small one, but it's not the only factor.
We also need to fix the high administrator-to-doctor ratio that adds costs.
Insurance companies provide little value and just extract money from people. They need to go away.
Many low-income people skip out on preventative visits because they can't afford them. This leads to high-cost illnesses later down the road that could have been prevented or mitigated with proper care.
So yes, doctor salaries are inflated, there is a shortage of doctors, and the AMA is a cartel that limits supply. But there's more to it than that.
With more doctors (and consequently lower salaries) the cost of preventative care drops, no? And perhaps just as importantly, the EASE and time-delay of getting an appointment drops.
Blue collar workers tend to wait, as you said, until an illness becomes critical - because they have to work 9-5, the same hours doctors work. With an additional 25 or 50% of MD workforce, we can easily begin offering preventative care services outside of 8-5, allowing low-income people to get the preventative care they deserve without affecting their livelihood.
We should strive for primary care visits to be available 7am-7pm (at least), 7 days a week, in every hospital/clinic in the nation. And specialist visits should be bookable in ~2-3 weeks max, not the 6+ week timeline many individuals requiring a specialist face.
I agree with all your points, and definitely the administration costs I hope will drop as we get better ML/AI technology. I don't personally see a realistic way to get rid of the insurance companies, but they can be quite harmful. Finally I also would like to double down that the "cartel" aspect is the single largest contributing factor.