You just do not understand the process. When workers separate envelope from ballot inside, there is no way to know which ballots are fake. The fake ballots dumped in the middle of night are all counted and become offcial vore count.
The process in not complex. Btw, like Trump has repeatedly stated, mail in ballots which you alluded to are a huge source of fraud. Everyone knows it. And now they’ve weaponized Covid, using it as an excuse to mail out zillions of ballots.
The same frauds are now trying to make it the normal thing everyone does. Mail in ballots should be highly restricted to the invalid and the military. They tell us it’s our sacred vote, as they make it as easy as humanly possible to undermine, cheat and defraud elections.