There's no way one person's data is worth a 25% discount surely. That strategy must be something like, have the sales we were going to have anyway (to attract c

There's no way one person's data is worth a 25% discount surely. That strategy must be something like, have the sales we were going to have anyway (to attract customers to the store), but make the card required to get them. At the supermarket I'm thinking of, with the 1-2% discount, there'll still be normal sale items that don't require the card, and then extra discounts that only the card gives you. Actually I just remembered the card earns you reward points as well (albeit slowly), so the total amount you "save" is indeed a little more.