This just occurred to me. We know they've cheating for decades now. There's various theories on they've been achieving this before 2020, but I just had a though. The ballot mule concept doesn't really NEED to have ballot drop and mail in voting to work. it just makes it easier.
Look at what happened in Atlanta and Philadelphia. You had hidden boxes upon boxes of fake ballots that were all scanned multiple times in Atlanta. Something which could have easily been done for decades. Just bring in a dozen or so boxes of fake ballots in "blue" precincts and have the lefty vote counters scan them all 10+ times until you achieve the desired result. Not like it's hard to do, as we all saw.
Then in Philadelphia, they had literal semi truck trafficking ballots form New York and New Jersey and dumping them in the middle of the night to be counted. Now, I realize that this was all done under the cover of night and spread out over several days in 2020, but it's not like they couldn't have also done this stuff in broad daylight in years past.
Remember, they're USED to literally no one paying attention or fighting back. The only reason they used the cover of night and spread it out over several days in 2020 is because they all KNEW that we'd all be watching like a freaking hawk. And in doing so we caught them in the act despite their added caution.
It's entirely feasible that they've been using ballot mules for decades. Just rather than dropping them off in ballot boxes, they've been running them to holding areas where they'll wait until they're ready to start cheating.
This also explains why 79% of ballots in Atlanta/Fulton County were reported as being fake or illegal a few weeks ago. The left literally does not have enough people to support their campaigns for office, so they have to fake support with ballot trafficking to remain in power.
Of course they were, how else can you explain such a well run machine....everyone knew what to do and did it with great efficiency. These are techniques that have been honed and practiced over many years; it didn't just pop up in 2020.