It would be even better if we had evidence that every one of the tens millions of mail-in ballots were filled out by and mailed by an actual legitimate U.S. citizen who voted only once and only behalf of his or her self.
Until that happens we have no proof the election results were valid.
As long as there are mail-in ballots, or stuff box ballots, every election is illegitimate. you can only verify a vote in person and with ID.