President Trump is suing Nevada over its recent decision to send absentee ballots to all voters, and warning the country "There is NO WAY (ZERO!) that Mail-In Ballots will be anything less than substantially fraudulent." Trump's critics argue that there is no evidence that voting by mail results in fraud. Trump is right that mail-in voting is a source of potential voter fraud, especially on the scale that is being proposed. But the bigger problem is not vote fraud - it's vote failure.