"Surprise" or balance billing was one way. Basically you go to a hospital that is "in network", get some work done, but it turns out that some doctor (often so

"Surprise" or balance billing was one way. Basically you go to a hospital that is "in network", get some work done, but it turns out that some doctor (often some side-channel like a radiologist) who reviewed your case was out of network. So your insurance doesn't cover him and the hospital sends you the full bill. Out of pocket max doesn't matter, because that only limits costs where insurance actually accepts the claim. It was outlawed by US congress this year (The "no surprises" bill), but there are some exceptions like ground ambulances, so I guess we citizens are supposed to remember not to take those to the hospital unless we are rich. Yes, its insane.