> Look, mail in ballots have been used for many decades.
Not on this scale, and not very successfully - see the article I have posted below.
Washington State has allowed universal mail-in voting for over a decade. There has been no proven case of voting fraud in the state for 10 years. I appreciate that Trump has been instructing his supporters to disrupt mail-in voting, but all that will happen if Trump supporters try to vote twice (as Trump has recommended) is delay in finalising results and lots of felony convictions of supporters who try it.
Doubtless you will claim that Washington State is somehow different, but universal mail-in voting can be safe, and is an excellent mechanism for overcoming voter suppression efforts. Attempted duplicate voting and fraudulent voter registration occurred rarely in Washington State up until 2010, but residents there now know well that they will be caught if they try it.