But the supermarkets gather that data, for sure. Several times I've bought a brand name item, then reverted to generic, then got offers related to that brand (just because I was buying based on value). I assume if they can establish a buying pattern with a few offers then often that will convert someone to the brand goods. (It's way easier just to pick the packet that looks like the one you got before than it is to look for the best offer).

One thing about returning to relative wealth is how much stress it removes from 'weekly' shopping.