Primarily, they don't. They idea that people come in droves to the US for care is largely an overblown myth. However, when it comes to Cancer treatment, the US is the best in achieving a successful outcome ie survivability. In other conditions, the best doctors come here to the US because they can make money here. But, they are very, very, very expensive and the vast majority of Americans could never get seen by them, let alone treated. They are doctors for the elite only and they will exist no matter what system we are under. In the few cases in which poor people come to the US for treatment, it's either: Their case is high profile or an anomaly, which will yield a paper or it's done pro bono for PR.