True, but they can tell when their card is put back in the wrong pocket, or upside down, or other tiny clues that hint of someone messing with their stuff. Kids sometimes think parents know more than they do, or “have eyes in the back of their head,” simply because kids don’t pay attention to the same details their parents might. Their parents can deduce what happened from clues, clues that the kids don’t realize they left.

A very careful child might get away with it, but if their parents are equally careful they’ll probably notice something is amiss. I guess it all comes down to “your mileage may vary.”