[tbrownaw]

Don't the industry-imposed rules for handling credit cards work that way (restricting use of data you already have) though?

Like, I thought a big part of why some stores do loyalty cards is because they enable tracking things that they'd get their credit card privileges revoked if they tracked that way.

[pessimizer]

Retaining credit card numbers is problematic in and of itself. Then you're just operating a skimmer.