Another viewpoint: I think the store should have the right to charge whatever they want and provide discounts in any manner they wish...and we as customers have the right to buy or to NOT buy from them.

Reasons why stores do this include
1. Interest charges they derive (ka-ching)
2. Understanding buying habits (ka-ching)
3. Ability to direct market that is less costly and more effective than advertising (ka-ching)
4. Holders of store credit cards tend to be better repeat customers (ka-ching)
5. Savings because those customers aren't using Visa, Mastercard, AMEX, etc on which the store would have to pay credit processing fees (negative ka-ching)

So, PF, maybe you you'll just have to learn to sew and make your own shirts in the future ... or take the Pixie's Challenge---go naked all the time.