> and in the other I hear stories of people getting a surprise 4-digit bill in the mail three weeks later, after already paying through the nose for insurance.

Lol. I wish. For me it was 5 digits. Closer to 6 than 4. And I had a $1,800/month premium for a family of 4. Spent multiple hours per week for months on end playing phone tag for the hospital and insurance company until it got resolved. Hospital billing also told me to not worry because nothing ever gets paid until both sides start suing eachother.

Yeah, this is peak efficiency. I just love taking up "resolving medical bills" as an unpaid part time job for the better part of a year.