[bee_rider]

These companies are making money somehow. If they are exploiting people more clever than me, then I'll probably fall for it too. If they are exploiting people less clever than me, seems pretty evil, I don't want anything to do with that.

[CPLX]

How they are making money isn't a secret. They take a percentage of the transaction from the merchant you pay every time you make a charge. It's effectively free from your perspective, the merchant is willing to share some of your money to allow you the convenience of paying by card.