[tpxl]

Legitimate question: At this point, what could a loyalty card possibly measure that isn't already measured on a bigger scale?

The cc/bank provider already gets an itemized bill, and they get it for everywhere you shop as opposed to a single store (so a superset of this data is already collected). This is in some (most?) cases already shared with stores, and even if it isn't, what can a store do with it the bank/cc provider can't do worse.

[hnlmorg]

Banks don’t know what specific items you’ve purchased from a supermarket. Just that you spent £123 at that store.

Thats where the paranoid was, around the fact that your individual shopping habits were being stored.

Also we are talking about the 90s here. So cash payments were more common.