There are about six supermarket chaions in the city where I live. Most people will struggle to guess which ones are owned by private equity (one isn't), but almost everyone can name at least a couple of hospitals that aren't.
It may seem unreal to you, but I can assure you that it actually happened at one point. It was a duopoly.
The history of Central America is essentially the history of these companies. Looking into it will give you more "understanding of the world" than you probably think.
It wouldn't be if the supply of health care were not artificially restricted by regulation.
> Medical care also often involves crisis situations
No, medical care sometimes involves crisis situations. But much more often it doesn't. A sane health care system would treat these two cases very differently. Care for crisis situations would be handled by insurance because that's what insurance is for: unexpected situations that you can't pay for out of pocket. But routine care would not. However, our system is not sane, and insists on bundling these two things together when that makes no sense.
Medical care also often involves crisis situations where you absolutely need care right now so you don't have much leverage. On the other hand, most of the time people have some flexibility in how much they eat, when they eat, and what they eat.