Similar reasons to why things are priced at $x.99 or why car prices are often quoted in per-month payments or why mail-in rebates make you mail something in rat

Similar reasons to why things are priced at $x.99 or why car prices are often quoted in per-month payments or why mail-in rebates make you mail something in rather than just give you a discount. Or why the dealer doesn't even mention the mandatory "prep" charge until after you've shaken hands on the deal. Perfectly rational people may factor everything in properly... but the world is woefully short of perfectly rational people.