how many of those 81 million were dead or duplicates?
Or 'corrected' manually by a poll worker behind closed doors?
There have been many reports of misprinted ballots in some swing states -- so many it doesn't appear to be unintentional.
When the scanners can't properly read a marked ballot because the alignment marks are too far off for the scanner, it's flagged for manual review. The ballots are shuffled off behind closed doors to a person at a special terminal who manually inputs what they believe is the voter's selection.
In the past, less than 5% of these ballots were ever reported, with 1-2% being the threshold for acceptable error rates.
We saw some areas with 60-80% error rates. That means the vast majority of ballots were recorded by a person sitting at a terminal entering whichever candidate they wanted ... i mean, however they decided the ballot was marked.
Just one more "no way!" item in the list of "how could this have been allowed?" questions in the Biden victory.