If your contention is that vote fraud is hard to detect and probably happens more than we know, look into statistics. The likelihood of detecting a single case

If your contention is that vote fraud is hard to detect and probably happens more than we know, look into statistics. The likelihood of detecting a single case of improper voting is low, but if there's a significant volume of it happening then the likelihood of detecting that it's happening at all is pretty high, at which point more detailed investigation can be done. Edit: this kind of ties back to the allegations of massive voting fraud in the 2016 elections. Lots of people looked into it and found no significant level of improperly cast votes. That leads to either a contention that it did not happen or a contention that all of the people investigating it were either corrupt or incompetent.