>> I don't think the hospital expects to actually ever get paid what they bill out

OH YES THEY ABSOLUTELY DO!

When I was in-between jobs I had a medical emergency and I was on the ACA around the first year it was offered. I was billed above medicare rates so I was on the hook for ~40k after out of pocket max. They told me this limit is what insurance has to cover but hospitals can still bill above it. First they told me they could work on the prices and asked for my last 5 years tax returns. When they saw that I had dividend payments they said they couldn't help me and I owed them the $40k. I think that was the problem because even though I wasn't working in their mind if I had investments then technically I was not in need so they set up four-year payment plan and paid every penny with no cost reduction.

I probably did something wrong but to this day I didn't know what I would have done differently. The only people I could talk to were the hospital and they only cared about the hospital.