Our cards all say to ask for id.. and we rarely get asked for it anyway.. we've asked a few cashiers about it and have been told that it's company policy one way or the other. Some places they are told to NEVER ask, other places they can ask if they want to, and some places can only ask if it says to on the card. For the most part we use debit cards so don't have to deal with it most of the time, and most places you swipe things yourself so don't get asked anyway cuz the clerk never has your card, even if it is a credit one. Personally, I like to be asked if I'm using a credit card (and if i have to hand over my debit card as well..) we like the extra security..
and yes, we've had to deal with id theft already... someone got hold of hubby's debit card info (one of them stolen hard drive problems..) last year and tried to use it.. luckily our bank caught the charges right off and called to verify (over $900 to itunes, air tickets in France and Greece...) and we got all of hubby's info changed and blocked their access and got all the charges returned...
unfortunately it was just before Thanksgiving and was the same week hubby's mom died and tied up all our funds (not that we could have gotten a flight in time anyway.. Alaska is difficult that way... esp around holidays...)
but we like id checks even more since then