The issue has been big in the news in the UK due adverts in the USA placed by right wing groups and the health lobby attacking the NHS (National Heath Sevice) in the UK. It's funny because a lot of the time people complain about the NHS in this country, but now the attcks are coming from another country everyone is rallying round saying how great it is. Personally as a minimun wage employee (classed as working poor I guess) I have had free health care, prescriptions and dental in the UK, and never waited more than a few weeks for any procedure - and none of those were even urgent. (This may be partly due to living in a rural area where the hospital isn't totally overstretched - I can't vouch for big city hosptials at all).
I know people on good wages with good health insurance in the USA who have to pay out large amounts (co-payments?) on top of their insurance that is supposed to cover them. I don't know any uninsured, but I don't imagine they're too well off. We had a guy staying a few years ago from the USA, Oregon I think, and he had a problem where his jaw would dislocate all the time. He was told he needed an MRI scan, but that it would cost $3000, which he said he didn't have, and he was uninsured. He was hoping to stay in the UK long enough so as he could get it done here, although as a tourist this wouldn't be strictly legal. How he got on I'm not sure.