If you read your credit card's agreement statements, that actually makes your card invalid. If you look below or around where you normally sign the back of your card it says "Not valid unless signed." You'd be hard pressed to win any legal matter where you proclaim the signature of your name is "See ID."
In addition, so may retailers here in the USA have swipe-yourself terminals. The clerks rarely, if ever, actually look at the cards now. It still happens, don't get me wrong, but how often does a minimum wage employee actually ask for your card? I didn't have it happen too often when I put my signature plus "See ID" on the back of my cards, so I just stopped.
I don't even sign my cards anymore. 99% of the time the signature on the back turns into an incomprehensible smeary mess after a few months in my wallet anyway.
I used to occasionally get puzzled looks from the few employees that would actually check the card, but now everyone in service is so overworked and miserable that they either never bother to check or don't care.