I don't think when your making the appointment you know that you'll be late... otherwise you would schedule for another time - it's not a big conspiracy by the tardy after all.
If I didn't make appointments when I knew there'd be a 20-30% chance of me turning up late I'd make no appointments at all.
If I didn't make appointments when I knew there'd be a 20-30% chance of me turning up late I'd make no appointments at all.