It seems unlikely they’ll replace mail in ballot scantrons any time soon, but with mail-in ballots you have increased vectors for fraud and stuff like the recent political interference with the US Postal Service.
One step forward, two steps back, I guess.
Disclaimers:
Since I mentioned mail-in ballot fraud, and the 2020 election just happened: I have heard of no credible evidence of widespread fraud during the 2020 election or Georgia runoff.
Electronic machines might be able to serve a useful purpose: I think the best option involves most people voting in person on paper ballots, despite universal access to mail-in ballots, and universal access to machines that print filled-out ballots for people with accessibility issues. Machines that print scantrons for everyone might be a net win if they reduce adjudication, and if people actually double check that the printout matches their intended vote. Alternatively, people could scan their own ballot at the polling place, and confirm it scans correctly. Either way, the paper ballot must be the authoritative record.
Now, they are scantrons. You fill out a big paper ballot, and the machine counts it. It's exactly the system I want in place.