Mcdonald's policy in drivethrough is to just swipe the card, hit credit, and wait for approval. We aren't even supposed to look at it other than checking to see where the magnetic bit is, apparently, because they(I assume 'they' are the credit companies) are "weary" (I assume he meant "wary", because if this happened frequently enough that they were "weary" of it, I'm sure something about McDonalds' credit card policy would get radically adjusted) of us copying the numbers down or something.
Inside, we never even touch the card.
Is there any *good* reason to not sign your credit card? The only excuse I've heard is "But then someone could learn to forge my signature" to which the answer is: "If you don't sign it, they can make up *their own* version of your signature."