Sometimes you need to spend a minimum amount, and usually this is hidden in the fine print. So if you wanted the discount, you would have to spend more than usual.This helps them in a few ways, depending in the iffer structure;Move their inventory faster (as food does expire)They collect more, or about the same amount of profit from the extra sales, even though rhe discount is hugeThe credit card companies advertise for these restaurants, to their millions of card holders. Hey, free (or cheap) marketing!People come in larger groups to get the discountPeople come more often for the limited discountThe credit card company gets a small cut from the usage of the card, rather than their customers using cash.If the customers forget to pay iff their card debts, the card company gets easy profitThats about all I can think of.