I typically show up an hour late at the doctors office if my appointment is in the afternoon. It gives the doctor some time to catch up on patients and when I show up I’m the next in line. It benefits both of us.
It's not a bill for healthcare. It's a punishment for wasting resources. Like at buffets where they charge you for uneaten food on your plate when you leave.
HCPs in socialized medicine often still get reimbursed based on activity, so a missed appointment means they miss out on reimbursement. Makes sense you ought to owe them for costing them money.