“Voting by an electronic device in person is pretty much effective in being fraud-free.
Voting by mail involves so much that is susceptible to fraud. The main two are:
1. Who knows if the mail-in ballot was completed by the person on the form?
2. The form is opened by a election official. Who know if that official is honest? Who knows if they discard or alter any forms that don’t go with the party/candidate that they favor?