Trump/MAGA either have no idea how elections work in mail-in states, or they're deliberately spreading lies and misinformation about it. I suspect both. As a Colorado mail-in voter, I'm getting pretty tired of their crap.
There is no such thing as a Federal election in the US. States run elections. MAGA simply wants to turn the US into a single party nation, just like any other authoritarian country.
" at a General Motors facility"
So may we assume it was a captive audience?