I don't really understand the loyalty card thing anyways. When I lived in the midwest, I'd just get a card from Kroger but never fill out the paperwork. I tho

I don't really understand the loyalty card thing anyways. When I lived in the midwest, I'd just get a card from Kroger but never fill out the paperwork. I thought I was being clever, but as pointed out, they still track you by your payment method. With that being the case, why do loyalty cards still exist? For cash buyers?