A blackjack dealer at a casino has like 40 cameras watching his every move and they're trained to constantly show their palms to prove they didn't do anything nefarious.

Hell, a cashier in a grocery store has a camera setup in place watching them.

If there was a will to have real elections, I'm not sure why it wouldn't be possible to have some form of monitoring in place that would prevent us from knowing who voted for who, but still have some form of visual record of the proceedings.