its not for marketing. it's for AVS verification. http://en.wikipedia.org/wiki/Address_Verification_System AFD's (automated fuel dispensers) are huge for fraud, since if i steal your physical card, i can just go fill up with absolutely no security checks. the pump is not manned, and no one actually looks at the card or anything. its not foolproof, since if i steal your whole wallet, then i probably have your ZIP code too, but its better than nothing at all i guess...