Knowledge isn't really going to be an issue for the parties most likely to try to swing elections, many of which are state-level actors.
The thing about the crudeness of methods used to tamper with paper ballots is that it's also similarly trivial for a bunch of volunteers including members of all different parties involved in the election to spot, and in many cases trivial to reverse.
The thing about the crudeness of methods used to tamper with paper ballots is that it's also similarly trivial for a bunch of volunteers including members of all different parties involved in the election to spot, and in many cases trivial to reverse.