[francisofascii]

I am afraid grocery stores will start this. (Or perhaps they already do.) Virtual sales for certain people for specific products. But it is hard not to pass up the huge savings the "bonus" card gets you.

[TheBeardKing]

Kroger does this with their Kroger card. They send you coupons for things in your purchase history, and similar items they think you might like.

[EADGBE]

Oh, the humanity!

[jonnytran]

Relevant xkcd: Customer Rewards https://xkcd.com/2006/

But we need another one where they use the data to exploit you.