Out of a reflex of distrust, I refuse to participate in any kind of loyalty program of the outlet of the large retail store around the corner.

I tell myself that by refusing to join the loyalty program (which basically comes down to scanning an anonymous loyalty card every time I make a purchase), I prevent them from adding my correlations (what products I buy, in what combos, at what time) to their data.

But since I normally pay by card, I guess they can (and do) already do that with my bank account information?

If I would pay with cash, they can still see those correlations per purchase, but they can't track my purchases over time?