Actually, if it exists we wouldn't be able to as the law forbids the collection of the information that could be used to verify it. Most often the fraud that can be found, because of the types of information that can be collected, is solely when somebody votes for a dead person who is still on the roles. This one happens both more often, and less often than each party thinks. It will become even more prevalent if we go to mail in ballots only (which for some reason the republicans seem to love, but is the most open to fraud including vote selling.) Anyway, it is a rather simple step that would reassure voters of the validity of the vote and would make such things as voting for dead people much more difficult. So long as the card is free and obtainable I see no reason for the constant fight on this one, it is a relatively straight forward thing. Nothing like an ounce of prevention, IMO. When you can see the problem before it happens, or see how easily it can be done, simple steps to stop it should be the norm rather than a battle. Better machines with paper trails, for instance.