That's how it used to work. I've seen invoices from the 50s where the cost to deliver a baby is $200. $100 for the doctor, $100 for the hospital.
With a 10x inflation adjustment, that's $2,000 total. That was enough money to deliver a baby in the 50s.
The profit margin there is insane.
An operating theatre cost many thousands of dollars an hour to run, the pre and post care is also very expensive. You may never need them (I hope you do not) but if you do it would almost surely bankrupt you without either socialised medicine (yay - sort of - another story) or insurance.
Certainly when things go wrong it can get more costly but the US consistently costs 2 to 3x more for everything AND usually has worse health outcomes. US maternal mortality is an embarrassment: https://www.cdc.gov/nchs/data/hestat/maternal-mortality/2020... .
Do you even know the ballpark of how much an MRI machine costs to operate? Yes healthcare was cheaper in the 50s, but this isn't the 50s.
Or they could keep prices high and "the poors" could just go die...?
Based on recent history I wouldn't bet against that outcome.
The root problem with healthcare in the US in general (with lots of blame to go around for the insurance industry, the healthcare industry itself, politicians, etc) is that we treat it like a commodity with elastic demand when in many situations it isn't, getting rid of health insurance (as terrible as it often is in practice here) with no other safety net in place would likely just make this situation far worse for the majority of people (basically anyone who isn't independently wealthy and suffers any kind of medical condition or emergency).
The problem is that due to highly variable costs between people, everyone has to play games to try to sucker everyone else into paying their fair share, because if they don't, they don't get paid at all.
Reworking health insurance to be insurance would fix this. HSAs are a step towards this, but not enough of a step to start seeing consumers actually change behavior based on price.