Fraud is the secondary hesitation with mail-in ballots. Competency concerns with the US Postal Service should be the primary concern. Has anyone tried to mail anything over the last two years? It is a crap shoot if it arrives on time or even at all.
Anecdotal, yes, but I've had zero issues with mail service over the last 2 years. Maybe it depends on location or something, but here it hasn't been an issue at all and I use the post office multiple times per week.