Many reasons can be cited to explain why it has been so hard in this country to get health insurance for every citizen, an idea proposed as long ago as Harry Truman. One is surely the powerful individualism that may have been more fitted to the early centuries of our history but ruinous today. This contributes to the lack of a strong socialist tradition characteristic of advanced European nations.
Another that needs more attention is the fact that white people do not want to be taxed for benefits that go to people of color, in the past meaning mainly black folks and today Latinos as well. This too has a long history. See: http://www.salon.com/opinion/feature/2009/09/15/race/
Add to this the unwillingness of Americans to support benefits that help others if it costs them something. Finally, add the political influence of huge insurance and drug companies that can use money, if not to buy. at least strongly influence legislation that preserves and increases their financial interests.
Doubtless other factors enter, but the ones mentioned are sufficient to explain why it will be like moving mountains with a shovel to get universal health care that is efficient and affordable.