Well, at the scales we're dealing with, healthcare is an infinite resource. Emergency rooms in the United States cannot turn anyone down, and even uninsured Americans will end up going to the hospital when something serious happens, because the choice is between debt and debilitating illness, people will pick the former.

Wouldn't it be a lot better if we could spend more resources on preventing disease by removing the disincentive for going to the doctor for early detection? Not to mention, with communicable diseases, herd immunity is a very real thing.