ID cards won't work because the only people that will have them are law abiding. unless incentive (or law) is forced upon businesses and everywhere else to not do business with people without cards... it's a completely useless idea. sure, it helps tie people to crimes across states (if they have a card) - but the simplest way is to just ditch your card or never get one. then you effectively don't exist and the processes developed to track you down (which have been modified since then to use ID cards as the main lead...) would have an even harder time tracking you down.
