Almost everyone in America is inusred.
This isn't true at all. There are millions of people who don't have any health insurance and far more still who are vastly under-insured (meaning their insurance isn't really worth what it should be in terms of actual care).
There wouldn't be much of an issue with health care if "almost everyone" actually were insured.
Good luck getting both reasonably priced and comprehensive health insurance down there if you have any major pre existing problems.
The entire idea of "pre-existing" is BS nonsense designed so that insurance companies can **** people over, which is their goal as a means to the end of making more money. Their main way of doing this is to sell you "coverage" and then if you ever have any claims to find as many ways to lessen what they pay out as they can, including technicalities and small print and every other trick in the proverbial book.
I find insurance of any kind to be a necessary evil at best and an unnecessary monster at worst. You should be able to pay a premium and KNOW EXACTLY what you're going to be getting before there is ever a claim - with no haggling, no small print, no debate over what is covered and isn't. As long as you paid the premium, they are legally obligated to pay X amount with no way around it.
Until that happens, insurance companies are just legalized con-artists who pull a version of the classic "bait and switch" scam over and over again to make profits. This is most insurance companies: "Pay us this premium and see how great our insurance is - what's that you have a claim well we don't pay out on that for reasons A,B, and C, and if somehow we did pay a small portion of it you'd only get this little amount because of reason D. You paid a premium in good faith thinking you'd be protected, but now that cat is out of the bag and you find out we don't cover you right when you need it and we don't care about you just about making money. Go **** yourself because we don't care if you live or die or suffer or what happens to you as long as we make money."
Universal healthcare is one of those things that makes so much sense that the U.S. can't possibly adopt it because that would ruin our reputation as the nation that is so powerful it can "afford" to make ridiculous decisions like not having universal healthcare - except the U.S. can't afford it, or at least those without insurance can't.