Postal ballot fraud incidences do exist, but are isolated
There are rare occasions in which postal ballot fraud incidences do occur. These events are isolated and do not occur frequently in the US. In previous elections, there have been isolated cases of postal ballot fraud. For example, such fraud occurred in the 2018 North Carolina primary, which had to be re-run after a consultant for the Republican candidate tampered with voting papers. There was also a case early in 2020 in New Jersey where two Democratic councilors were charged with alleged fraud in relation to postal voting after hundreds of ballots were found stuffed in a post box.
Postal ballot fraud occurs frequently and is not at all isolated. In September 2020, Facebook photographs of "dumped" ballot envelopes in California were shared thousands of time on social media with claims of election rigging.