I haven't worked in a bank, but I did work in a market research firm that was gathering a lot of data about retail sales. In addition, I have worked in small businesses that processed payments from customers via credit cards. In the U.S., the payment processors (whether banks or credit card companies) don't even receive information about the items sold; all they get is the amount to be charged to the customer's account. The typical retail store simply doesn't have the item information available in the same system that performs the credit authorization and reporting.
In our market research company, we were receiving data from a variety of retailers, including large grocery chains (with hundreds of store locations), and on-line merchants. The retailers could report details of the items sold to a customer; as a "data aggregator", we could (with some difficulty) associate each retailer's customer IDs to the households, and build up a picture of each household's buying habits. But this information flowed from the retailers, not from the payment processors.
I don't, at this time, have any concerns about my credit card company knowing too much about my buying habits. I do have some concerns about the retailers. That's why I refuse to be locked into a technological solution where both the reading hardware and the reading matter come from the same vendor. Instead, I buy my books from many vendors, and read them on a platform provided by developers who have no direct relationships to any of the retailers.
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