The sad thing is they all are doing it and don't even need you to use any of their "discount cards" or whatever, they can just do credit card correlation with third parties and achieve all the same results without you ever agreeing to it. I compromised and got a card but never signed anything or registered it, so I still get discounts but I can't, for example, enter my phone number (I have to have the card for scanning on me). They are correlating the data anyway so I might as well save a buck or two.