@KitaYama
It sort of depends on what kind of hospital you go to. A certified trauma center cannot turn you away for life-saving action but there are "boutique" hospitals that don't have that requirement. For instance, my wife had hand surgery at one of those boutique (i.e. specialty) hospitals. If they aren't equipped for trauma response, they can legally say "no" and get away with it.
Many years ago, my father died of a coronary event, a myocardial infarction, and was transported by ambulance to a trauma center. He passed away but not before doctors worked to get some sign of life from him. When he had been unresponsive with no heartbeat for about half an hour, they had no choice but to declare his death. We were later told his heart muscle had so badly damaged itself that nothing could be done, which implies that they must have cracked his chest open to know that. We never once got a bill for the hospital OR the ambulance ride, and I know that because at that time, my mother had already started down her final path to dementia. We had insurance that would have covered Dad's costs, and I handled the estate because Mom could not. But nothing ever came our way.
There ARE horror stories about incredibly strict hospitals, but there are also true stories about hospitals that try their best to keep helping people. The horror stories, however, are reported by sensationalist-oriented news stations that seek overly ghastly headlines because that is how they keep their ratings. The success stories get a LOT less broadcast coverage. And therefore, I would suggest that you take into account that there is a headlines, ratings, and sponsors motive behind some of the more horrible reports. Which is not to say they don't happen. But the reporters pick and choose the stories to emphasize based on just how sensationalized they can make it.
You also find stories about illegal immigrants who go to emergency rooms precisely because they know they cannot be turned away but they have no money for a traditional doctor. So no continuing care, no regular-practice doctors, no regular medical history. And during the height of the COVID pandemic, no capacity. We have a friend who is an emergency room support person - gets called in when her specialty is needed. She has told us of what often seems to be a never-ending stream of poor people who can only be helped so much before the hospitals run out of resources and the hospital people run out of stamina. And yet they never run out of patients.