I was always impressed with the simplicity of the purple finger like the Iraq election the US helped with. That could eliminate repeat voters. Then, put through a bullet proof (or shall I say dumbo-crat proof) I.D. system.
They ink the pinky finger in India, too.
Why not here?
We all know why...
Paper ballots.
Voter photo ID required.
Purple thumbprint on ballot.
Two-party ballot transport and counting.