My thought about cash back cards is that you're going to buy stuff anyway, why not get a bit of it back. Yeah, maybe sometimes I buy a couple extra things because it isn't "cash", but most of what is purchased would be gotten anyway. I haven't paid a dime of credit card interest in probably 30 years, that's a fool's game.
Yeah, I'll take my $250 check from Costco and enjoy every dime.
The Costco card is what we use for gasoline and diesel. I don't really see how getting a few cents/gallon back doesn't work in my favor. I'm going to buy it anyway, and every little bit helps. Costco gas around here is the cheapest, plus the money back. Win, win. But we only fill up there when we are at Costco anyway.