> I don't have any insight into how they use the data, but why would they offer free things (restaurants offer appetizers, grocery stores offer discounts, etc)

> I don't have any insight into how they use the data, but why would they offer free things (restaurants offer appetizers, grocery stores offer discounts, etc) unless the value they received was more than the cost of the incentive? Ignoring selling the data to brokers, it's not hard to think of some ways to use the data that's beneficial to both you and them: - Inventory management: You buy something low demand, but you do it consistently. If they can match up all the purchases of that item to specific folks, and they know the general frequency at which people buy that item, they can ensure it's stocked when you need it, without the need to greatly overstock it. If you stop coming, they also know they may be able to reduce that stock safely. - Price sensitivity: They do a price increase. Which customers have stopped purchasing the product? Do they need to do a sale on the item for you to purchase it again? Do they need to drop the price? This is more of a benefit on their side than yours, but knowing the most frequent purchasers stopped purchasing it due to an increase could lead to a decrease, where this is harder to determine without good data. - How effective are their sales? Are they targeting them correctly? The discount they offer isn't really a discount. It's a price hike for folks without the loyalty program.