> In theory you might have insurance, but while unconscious you might still ‘pick’ an out-of-network hospital or anesthesiologist and end up with huge bills. If you know the right people and can afford it, you could then negotiate this down. Maybe. I know several smart Americans that had to live from their car while they sorted out financial issues.

This particular issue is, supposedly, fixed. See:

https://www.cms.gov/nosurprises/Ending-Surprise-Medical-Bill...

According to a sign at a hospital I read recently, this protection cannot be waived in the ER. The ER is simply not allowed to issue a “surprise” bill. (Which still permits outrageous bills, but insurance pays them per the usual rules.)