In the states the company running the payment system (Visa, Mastercard etc) is a separate company than the supermarket and so they can’t necessarily group together all the purchases a single customer makes, let alone if they pay cash

Imagine a taxi driver, he might overhear your name and the address you’re going to, but that doesn’t mean he can go look up every taxi trip you took,

Now if you have a loyalty card there’s a single identity to group and market towards

Now take this all with a grain of salt, your system may be different, but the technique spread across markets