The White House site gives a total of 1071 instances of voter fraud. Hardly an overwhelming problem.
The voter fraud site said there were 8 cases of fraud using mail-in ballots in 2016 and 7 in 2018.
It isn't really feasible. Trump talked about a foreign government printing millions of ballots. It wouldn't work. You would have to print different versions of ballots for every state, county, Congressional district and so on. You couldn't print a million ballots with just Biden and Trump on them. Then you'd need to have a way to get the right kind of ballots mailed to the right addresses or dropped in the right drop-off boxes.
Have you seen a mail-in ballot? Mine has an envelope which I must use to return the ballot -- and that envelope has my name and address as well as some computerized image which identify it. I must also sign that envelope so they can check my signature. Even if an intelligence agency could master the thousands of kinds of ballots needed, I doubt they could duplicate the information on that envelope.
As for someone opening envelopes without getting caught? It would be hard to alter the ballot I have. I have to color in a circle completely; so someone would need to undo my marks and fill in another circle. He would also have to have a way to reseal the envelope in a way that made it look as if it had never been opened -- or have new ballots and envelopes that matched the ones sent out.
Your scenario seems highly unlikely to me. There are usually people from both political parties when ballots get counted. Refusing a party the right to have an observer is a serious offense. I also think most people who work as election officials have done so for years. The mother of one of my friends has worked in elections for years -- I don't know if she will this year or not.
If anything, voting by mail might be more accurate. Haven't you read stories like the box of ballots found in a woman's car after it was too late for them to be counted? She was given the job of taking ballots from the polling places to a central spot where they were counted -- and oops, she forgot that box. Now that could raise suspicion especially if she was one party and the precinct with the missing ballots was predominantly of the other party. It could have been simple human error too.
Trump is doing what he so often does: Create doubts about the integrity of others, create suspicion about others. He tries to undermine trust in anyone except in him and the people who flatter him. If you can daze people enough by creating chaos and doubts, they're apt to want a "strong" figure to trust.
I don't trust anyone I see bad-mouthing others without any evidence. If someone tells me, "You know Harold doesn't like you," I don't believe it, not if the last time I talked to Harold everything seemed fine. If he says, "I'll tell you what he said about you if you promise not to tell him I told you," I say no, I'm not going to promise that. Such a person is trying to poison me against Harold. Saying he wants me to keep it a secret because he doesn't want Harold to get angry with him doesn't work -- if Harold is such a nasty person, why would he want to be friends with him? Odds are too that he's bad-mouthing me to Harold.
