That's a good question. If they were asking "Did you see a person who looked like (description of JustSomeNobody)?" That seems like it's clearly the vendor's in

That's a good question. If they were asking "Did you see a person who looked like (description of JustSomeNobody)?" That seems like it's clearly the vendor's information, because it's asking about his memory of what he did or didn't see. It doesn't seem right that your memories should belong to someone else. On the other hand, if he happened to have a photographic memory and remembered your exact credit card number, expiration date and CCV, we would all say that that is not his information to give out however he wishes. So, yeah. I don't know what point I'm trying to make except maybe introducing the idea of data "ownership" just creates more problems than it solves.