2/3 childbirths we missed one (tiny, in both cases) medical bill and it ended up in collections.
We were getting like 3-5 letters per provider per visit, and many visits resulted in bills from multiple providers.
"NOT A BILL" (so why the fuck are you sending it to me?) same thing again from insurance for some reason, incorrect bills we had to fight, insurance refusing to pay on things they should so that drags out for months and you're getting "FINAL BILL" in the meantime but the hospital billing people are telling you not to pay them until insurance is sorted out.
Many providers sending a bill exactly once and it goes to collections if you don't pay in 30 days, no calls or follow-ups (that's how both of ours ended up there—again, they were tiny, we'd have paid them instantly if we'd known about them).
Bills showing up two months after a visit and you've had 30 medical appointments in the last year so you can't remember WTF it was for. I think in one case we were still sorting crap out from the birth and prenatal care when the kid was 6 months old.
Hospital requiring full payment months in advance for the births. And getting it very wrong in one case (on the high side, of course—every billing error is in the hospital's favor, super weird how that works, bet it's just an accident and not them being actual no-bullshit criminals, though eyeroll) because they refused to use our version of what insurance would pay (which was correct) and basically just made up a number.
Total fucking mess. Horrible experience every time. Can't wait to get to deal with this horseshit when one of us is actually, seriously sick. I've added hospital billing departments to the list of medical-related folks I truly, sincerely wish the worst on, and I mean the worst—show me the headline, I'll open the champagne. They're either shockingly incompetent in ways that mess up people's lives, or they're malicious. Maybe both.