As if identity theft isn't rampant enough...
BTT
Yes, but an unquie ID lets you instantly see that its been voted twice. Thats why a provesional ballot would be filed in such cases, while it is later investigated.
It would be pretty easy to nab people committing voter fraud under this system and throw them in jail. It would catch multiple votes, votes across borders, illegal alien votes, and more.
It is also simple, and requires minimal change. Require a Social Security number to vote, and simple electronic voter registration (not voting, just registration).