@NathanG - RFID smart cards (radio frequency cards) are particularly vulnerable to hacking. These little cards are used in military and transportation settings. I read the other day that hackers had succeeded in breaking the encryption codes in these little devices. So to follow up on your point, even these cards are not as secure as once thought.
That’s too bad because I have always been a believer in these RFID cards. Some of them have been used to track birds in flight. At one time I thought it might be a good idea to have really tiny versions of these cards that could be placed in wristbands or watches that kids everywhere would wear to aid law enforcement, in case a child is abducted.
There is good and bad in smart card technology, but we just have to focus on the positive uses while being aware of its dangers.