If one person votes repeatedly in a walk-in election at least they have to walk from one precinct to another. Election observers on a mail-in election have to be present at the reception of the mail for weeks or even months instead of just one day. The elections office is a partisan office filled with employees who care deeply who wins and it is the election observers that are necessary to maintain fairness. There is no way to prevent the US post office employees from accidentally or purposely influencing who gets ballots when, and how fast they are sent in — another subject of much newspaper comment in Washington state when the King County election office lied to the public about when it mailed overseas ballots, mostly to US soldiers.

Countries that are new to Democracy know all these very obvious things and would never stand for mail-in elections. Instead, they rely on simple expedients like applying ink to people’s fingers when they vote and counting votes publicly.