[Anderkent]

Well, the question is whether the increased safety (assuming your neighbour doesn't share your voting preference - I don't know if vote counting is usually done by two people from different parties, or something) is worth the increased cost. It seems unlikely to me.

[nxc18]

It might be possible for aligned individuals to conspire, but it's unlikely.

When the community is sufficiently engaged, either you have differing political views and thus don't have to worry about conspiracy, or everyone has the same opinion and the conspiracy would just reinforce the true outcome.

Regardless, the possibility of that conspiracy is another great way to encourage participation. Republicans and Democrats both have an interest in the other side not tampering - combined that turns into a pretty strong interest in removing tampering altogether.