>>Of course they could have my complete record whenever they wanted - I'm paying with a debit card, it has my name, and they must keep that on the record for at least a while in case some fraud was going on.
>
>
>Yes. But they don't have any demographic data about you, which is a big part of what they are looking for.

Much good it would do them. There's no way for them to understand from those data that

- the few times I bought things I never bought it was the cashier who asked me to borrow my card to another customer
- no matter how many times I buy the same thing, I will not buy it if the price is not clearly visible
- they can draw absolutely no conclusion about my habits regarding items they don't have
- they have no clue as to what am I buying in the other two or three groceries in the area

And even if they had any demographic data on me, I love to imagine that I don't fit any profile. I guess I'm falling beyond the three-sigma interval in many cases.