2. It opens up the process to more errors

Humans aren’t particularly good at repetitive tasks like counting ballots. Machines were made for that, said Wendy Weiser, who directs the democracy program at the Brennan Center for Justice.

Weiser said there aren’t a lot of studies about the accuracy of hand-counting, but a 2012 study looked at error rates for a popular hand-counting method and found a 2 percent error rate. “There are multiple elections won or lost by much less than 1 percent,” she said.

If you’re entirely hand-counting ballots, then voters fill out their ballots entirely by paper — which opens up a lot of room for them to make mistakes.

The disability community in particular opposes all-paper elections, said Michael Morley, an election expert at Florida State University and contributor to the conservative Federalist Society. For example, if someone has arthritis, it can be difficult to mark the right spot, make the mark dark enough or erase marks completely.