How does it work? Do you need to apply somewhere that and get certified for "cannot pay" status? Do you need to do it before the bill? What if you can pay 1000$ but cannot pay 2500$? What if you can pay but after paying it your life standards lower significantly? What if you have some money and you were about to go to college but an appendix happened and now you cannot affor college?
Since the hospital takes a loss in those cases (and has to, since they have to treat everyone), everyone else's cost of care goes up to subsidize the loss.
As someone who's family has been in that situation before, not it is not. We had a $35,000 bill forgiven entirely because we couldn't afford it. The process was certainly stressful, distressing, and we shouldn't have a system where it happened in the first place. That doesn't change the fact that the end result was forgiveness.
That's about it.