One of the force driving salaries up is strict control of immigrant doctors. Its is million times harder to qualify to work in US as a doctor compared to immigrant software engineer.
It's a huge issue in my opinion. Doctors who learn in Europe simply can't work here unless they get qualified in the state they want to work in, which is a waste. You see doctors from India and various other Asian countries because it's worth their effort to do so. But the USA should open it up to doctors from other countries to more easily work here. Simply passing a "Certification" or something should suffice.