I spent some time as a poll official. As part of that job, I had to help people vote paper ballots with fill-bubbles who couldn't figure it out for themselves. Of course, I was forbidden from telling people who or what to vote for, or from offering any comments. The marks also had to be made by the voter's hand. Most of the people with trouble constantly made illegible squiggly marks all over the ballot instead of bubbling in neatly. People who did manage to vote by themselves also had problems. I was able to see their voted ballots because they ignored the instructions to keep the ballot concealed in the provided folder. Instead they waved the ballots over their heads for everyone to see. These too were often marked illegibly. The poll-watchers could only shrug sympathetically to me when this sort of thing happened. Voters have three tries to do it right and after that, too bad. A few people managed to get past the official guarding the ballot box and dumped their illegible ballot in before the official could react. There's another source of bad ballots.
I think New York might be trying to solve problems like these.
Other problems we had were cases of the adult child, who could barely speak or read English, was helping an elderly parent who couldn't speak or read English at all, and so I had to help. I very clearly caught many of these sons pointing to particular candidates or measures saying "Mark here". They were warned several times about this, but ultimately I couldn't do anything besides accept the ballot. Again the poll watchers just shrugged.