I recently started seeing advertising related to products that I had purchased at a large US supermarket. I did some digging on the payment card networks and found that they are sent a lot more data that I realized. Level 3 data (the highest and most complete) sends product data about what you bought to the payment network (Visa, Mastercard, Amex, etc.). I have no idea what they do with this data and who they sell it to. I love the protection of using credit cards, but if merchants go cashless, privacy goes with it.