The real truth of what happens is substantially more complicated due to America being made of 50 states. The medical debt numbers are highly debatable (Related Snopes) and do not account for Regional differences. In some states such as New York there are catchalls/emergency funding so that usually anyone making below low six figures can get their bills paid. Other states make collections difficult such as New Jersey not allowing reporting to credit agencies, making ignoring a debt kind of a non-issue. Then there are states such as Florida that require the barest of insurance to keep rates low and provide no patient protections, so when an accident does occur out of pocket costs can be huge as your insurance covers nothing. In all these events the Hospital assumes that big pocket insurance is paying first so they break out the expensive menu, when they realize they can’t get blood from a stone they are grateful if you cover their wholesale price.

about half a million Americans go into bankruptcy due to medical debt each year.

That's a huuuge shame for a country that calls itself civilized and developed etc.

Luckily there doesn't seem to be any large desire in the general population to move away from the NHS. Even the most conservative people I know support it (and I live in a pretty conservative area).

Some of our political parties however seem to pretend like they support it while quietly trying to undermine it. Let's see what Labour do in the coming years.