Ah, yeah. I do agree that that's a weakness here: you hand your ballots to the poll worker, they void it out, and that's placed into a bin to be counted at the end of the day.

Potentially a poll worker could use that opportunity to look at your ballot and see who you voted for. Perhaps it would be better if you were allowed to tear the ballot in half yourself and drop it into the slot but there may be a reason why it's not done that way.