It's also fairly easy for us techies to grasp the hacking of computer systems. But we often forget how insecure and error prone paper systems can also be:

http://www.youtube.com/watch?v=sJfj9ySYg0Q

Massive voter fraud could be happening every election - it's pretty easy to vote fraudulently and there is almost no way to find out after the fact (I've done it unintentionally). For whatever reason, we are insanely afraid of hackers pushing an election over the edge, and yet we don't even ask for photo ID at the voting booth.