Yeah. And that was the thing with chad ballots.
A chad ballot is essentially a computer punch card. Holes were punched in a physical ballot to allow it to be read by a computer, or mechanical machines. Either through a physical contact made through the hole or later light shining through it. It was an early approach to the same scanning marks on a page thing the scantron did. But also an attempt to eliminate the earlier devices’ sensitivity to marking. Where things needed really specific, non perminant marks and perfectly filled bubbles.
Problem being those little punch outs caused all sorts of problems. Pre-preforated chads could fall out without someone deliberately marking them. An incompletely separated chad could fold over the hole as the sheet was fed, causing it to read as closed. Incompletely punched holes read as closed. And so on.
All of which prevented the device (and still prevents them cause we’re still using chad ballots and they’re still causing problems) from detecting a problem with the ballot. So you you can’t reliably do that important step of rejecting roached ballots. And in checking your physical ballots, all that unreliability in poking holes turns into a bunch of rejected ballots and arguments that votes for candidate A are really votes for candidate B or aren’t votes at all. But random chad problems. So auditing things becomes much more complicated.
Perminant ink marks on separate paper ballots. Scanned and counted by an electronic machine that maintains separate paper and electronic records. With the original ballots preserved and stored/controlled separately has turned out to be the best way to go about this. And you can add additional layers of redundancy as well. Like scanned images of ballots as a separate record, and receipts or take home copies for voters.
The biggest issue when the machine is the ballot. Is it drops the most critical layer of redundancy. The physical ballot that’s got no contact with the machine. So you skip a couple of the checking steps, and all the records directly involve the machine. So if the machine’s a problem you got nothing independent to check it against.
