I laid a bike down in '13 and landed so hard on my right side and arm specifically that I broke #s 7, 8, 9, 10, & 11 ribs.
Four days under observation with a chest tube for the lung puncture and I was released. If you've broken enough ribs at once you can understand how painful it can be to answer questions for a few hours at least. When admitted I hadn't explained my medical coverage between painful gasps. Several weeks later I received a bill for >$19,400.
I called and was told there'd be no interest charge. I mentioned surprise that my insurance didn't cover any of the bill. "You have insurance?" "Talking wasn't easy when I arrived." "Yeah, we didn't pick up on that then. Let me call your carrier." A week later I received a statement. BCBSM offered $5,600 and it was accepted. I had to pay $28 for my part.
I'll go dig one better; medical billing is a racket. There are seminars given to teach separate billing for items included in another code. You'd think masks & gloves for surgical staff would be included with bypass surgery. Not the best example, but you get the idea.