I disagree with a lot of the article, but they do bring up the "hanging chad" debacle. Digital voting helps prevent these cases.
Seems to work well enough without any sort of voting machine involved.
- cross is too light
- shape drawn is not a cross
- more than one cross
- one cross drawn, erased, and redrawn elsewhere
- one cross drawn, crossed off, word "nevermind" written next to it, and then a new cross drawn somewhere else