Sounds as if a programmer could bypass that though. It could show you what you did, but then swap the vote on the way to electronically recording it.
At any stage of the process, it can be changed. If it shows it to you, so what? You say, yep that’s right, and it goes on to record the vote differently.
It is easy to program cheats in, but difficult to program in inked out X’s and people’s initials. The final tally would always be what is on the paper and the paper totals should always equal the number of people who physically voted.
P.S. It is easy to erase electronic bits, but not so easy to erase the printed paper.