This is not entirely accurate, business reply mail can be parcels as well. Brother and HP ink returns are 2 I can think of off the top of my head. So we see packages with those labels on there all the time. The company will pay the postage automatically through their account (if they're large enough to do BRM they have an account) and just get the mail delivered. Honestly I don't know of anyone at the PO that would say something about it, we'd just laugh like "well we're getting paid for it regardless lol"