1 The private, for-profit insurance companies, hospitals and pharmaceutical firms.
In the USA almost all of these institutions are deeply in bed with the bankers via stock dispersions, derivatives, and medical debt financing schemes. These entities will NEVER give up a huge profit center like the trillion-dollar health market. They will pull out the so-called nuclear options, and if the pre-existing nuclear options don't work, they will invent new ones.
A further barrier is the pharmaceutical companies, who force your government, insurance companies, and individuals to pay rates for medications that are in many cases dozens or hundreds of times what the rest of the world pays, even though the medicines come down the same assembly production lines. In Sweden, hepatitis C drugs are free straightaway to the citizens, as the goal of the government is eradication. These drugs cost the Swedish government 3000 to 6000 dollars US per year in the short term, and saves money in the long, as the cure and survival rate is incresing. The VERY SAME drugs cost your Medicaid/Medicare and your private insurance companies over 40,000 dollars, A private citizen who has to buy at full retail, will spend over 100,000 dollars per annum.
2 The state of the health of the American people would overwhelm such a system, without drastic, systemic changes to the health of your people.
I could go into a Walmart (personally I have never stepped foot in one, even when I visited the States or when I lived in NYC) and in several hours, I would see more overweight, physically ill individuals than I would see in months of walking on Drottninggatan, our busiest central Stockholm shopping street. More than 50 percent of the American population will have diabetes or pre-diabetes by 2020, according to a new major report (
http://www.ntdaily.com/?p=14672 ). Your cities ere designed to only be accessible via auto traffic, thus making walking to work or shops either logistically impossible or in many cases, dangerous.
The level of bio-physical attack you are under is staggering, the vast bulk of your food contains GMO, sports are something to watch on telly, not actively participate in, the use of high fructose corn syrup is off the charts (new studies show that cancer cells use HFCS like super-fuel to spread
http://www.reuters.com/article/idAFN0210830520100802 ), the vaccine rates are insane, (even ones that we in the EU have banned due to many deaths, such as the new Swine flu), and almost 90 percent of your country fluoridates your water, something we outlawed over 40 years ago, after a brief trial showed many negative effects, especially on cognitive brain development.
3 The culture of consumption, and "more is better" ethos that permeates the American zeitgeist.
We have a concept in Sweden called 'lagom'. It is fundamental bedrock to our culture and psyche, and roughly means 'just the right amount, neither too much, nor too little'. It is a balance, a way of offering help to all, but not condoning greed, all within our holistic bio-sphere of Swedish soil, natural resources, and the ancient knowledge of moderation in life. This, to many millions of Americans, reeks of self-denial, of a retreat in the face of new conquests. Nature and nurture to us means living as fellow life, in a fragile plane of existence, and this is philosophy, if anthropomorphized into a human being, would truly be 'persona non grata' at millions of Americans' tables of ideas. This will manifest itself in the heath care system by chronic overuse, rampant fraud, unfair distribution of scarce resources, and a horrific lack of service for the intended consumer.
Bottom line, there is huge money to be made in the American system by serving cheap, chemical-laden food that is mass-produced, promotion of the petro-fuel car culture that leads to low physical activity, then further huge profits to be made in sucking dry the sick humans that result from such unhealthy, unsustainable lifestyles.