It wouldn't just be that their vote would be revealed, though, it would be that then the bad actor could contest the vote, claiming that they were the voter and their vote was counted wrong.
But if people were in the habit of destroying their unique code immediately after the results are posted, then they at least have plausible deniability. "No, I burned that piece of paper yesterday. Can't remember what the numbers were."
You are right. I failed to thoroughly think it through.
But I think I would rather have a system where you need to intimidate and coerce people en masse in order to change the vote than a system where you just need to coerce the handful of people who are responsible for counting the vote.
It wouldn't just be that their vote would be revealed, though, it would be that then the bad actor could contest the vote, claiming that they were the voter and their vote was counted wrong.
But if people were in the habit of destroying their unique code immediately after the results are posted, then they at least have plausible deniability. "No, I burned that piece of paper yesterday. Can't remember what the numbers were."