Because as a well-compensated engineer with good insurance, who pays his bills when possible at point of "sale"/leaving the office, some how in the last 20 year

Because as a well-compensated engineer with good insurance, who pays his bills when possible at point of "sale"/leaving the office, some how in the last 20 years I've had several occasions where mystery charges came in the form of paper bills that I had to make several calls to get to the bottom of, sometimes 3-4 different amounts on different bills. The US health care system is crazy in many ways, but hospital/doctor office billing and admin is one of the more egregious. I firmly believe they make money by people simply paying every statement they get, some of which the insurance company will later take care of anyway, just out of fear of these "collections"