In order to sell policies in MA, health insurance companies must submit plans to the state for approval. As a result, prices and options are much more reasonable than under a typical health care regime. In addition, the state provides assistance for poor individuals and families to buy insurance.
The flip side is that all MA residents must purchase insurance (the "individual mandate") so that insurance companies can spread their risk across a pool of both healthy and sick people. Otherwise, the majority of people buying policies would be those with pre-existing conditions, and the insurance companies would go bankrupt.
Why can't the rest of the country do likewise? Because of Americans' traditional hostility to any government involvement in the economy. It is typically portrayed as an invasion of privacy and an instrument of control. You should hear the arguments that were made against Medicare - you'd have thought the country would become a Stalinist gulag! Right wingers organized a campaign called "Operation Coffee Cup" to whip up opposition to the proposal. Future president Ronald Reagan even cut an album to support the effort (Ronald Reagan speaks out on Socialized Medicine - Audio - YouTube
And now we couldn't imagine eliminating Medicare. Yet some people don't get that this is national health care for the elderly and disabled - hence the "Keep the government out of my Medicare!" signs at protests against Obamacare. Ignorance kills.
I must also say that President Obama did a p*ss poor job selling the program to the public. The facts speak for themselves: we spend more than any other advanced democracy on health care, yet are much less healthy by any measure. Pay more, get less! But Obama really didn't lay out the case in persuasive way. Did you know that before the ACA was passed, 50,000 Americans died every year because they lacked health insurance? If not, you're not alone.
We also have this irrational hatred towards all things French, especially since they refused to go along with the invasion of Iraq. So there's a reflexive objection to the idea of emulating the French system, even if it would benefit millions of Americans. Freedom fries for all
Doctors in the US make about twice what French doctors earn, BUT there are a few caveats. Medical schools in France are free, so if you are good enough to get in, you don't have to worry about graduating with $200,000 in debt. Malpractice is also not a major issue in France like it is here, for several reasons. Yes, tort (injury) lawsuits are excessive here, but the larger problem is that incompetent doctors are allowed to continue practicing medicine, even if they have numerous complaints against them. State medical boards are generally made up of doctors, and are reluctant to rule against a colleague. 85% of doctors who have been found guilty of malpractice 4 or more times are not even disciplined. As a result, a few bad apples cost us all a fortune: 5% of doctors account for 53% of malpractice awards. Not only is this expensive, it's also scary as a patient!
Yes, that's the point - individuals and small businesses face a "take it or leave it" proposition in regard to medical insurance. We simply have no bargaining power. OTOH, those who are able to negotiate as a group (such as unions and larger firms) are able to get much better policies. There is strength in numbers, which the single-payer systems use to great advantage.
ETA: One point I forgot to make earlier - if you need any proof of the extent to which insurance & pharmaceutical companies manipulate the system, note the fact that Medicare Part D (prescription coverage) does not pay for mail-order medication from Canada, even though it would save taxpayers billions.