What do you want?
Tonight an woman came in, made her purchases and was checking out when she had a fit. She used a credit card and the cashier asked to see the back. Of course this is a standard practice to ensure that the cardholder is indeed the person using the card. This lady went berzerk. She was upset because she says we usually don't check her card but we did this time, and we should be checking all the time. I told the reasons that we check, and that the cashier that she went through checks all signatures. She was still freaking out and left the store. She called later to complain again and to ask me what our credit card acceptance policy is. I re-explained and she again told me how insulted she was that her card was checked, yet we should be checking everyone's signatures. So which way did she want it? She really would have been upset if her card wasn't signed - we would have had to ask for her ID!
Funny though, I usually say "And thank you for asking" when they ask for a Drivers License.
Heck, so many of those places have the "you scan your own card" things these days, that there's not much more protection in a retail environment than over the web.
When I worked retail, I'd usually say something about "Well, you'd be really mad at us if you weren't the real you, now wouldn't you?" and that seemed to at least give the customer something to 'mull over'.