I'm not sure what your point is.
The US can service demand, that is what you want in a system. That is the benefit of the US system and a problem in many universal systems. You can't call all doctors here greedy bastards, many of the same people that would become doctors in a universal system become them in a private system.
Some doctors are in it for money, probably a really good percentage here, but if you can't get enough altruistic doctors to satisfy demand, regardless of system, you're going to have to use external motives, such as money, at some point to get enough in. If you don't, well, you have long lines and people lacking service.
Anyone advocating moving to universal health care should understand we're trading one set of problems for another. Our system has major problems, but moving to another system isn't going to turn out better simply because it is based on a particular idea. If you build it badly, it will still have major problems that will need correction.