Overvoted ballots should NOT pass go. NOT collect $200. If the machine notices an overvote, it's a bad ballot. So sorry, but your vote doesn't count. Either get better at filling the bubble in next time or get a new provider for the scanners/machines.

The problem is that no matter what, there's always going to be a way to cheat. Let's say that ballots have a unique QR code attached so you can't run the same ballot more than once. This is a cool idea. Problem is, how is it checking? You'd need a hashed list of the QR's on every single machine that needs to be updated for every single election or they would need to be networked and hit a central server for the check/verification process. Who runs the updating of the software? Can we trust them? Who runs the server? Can we trust them? What if there's a network outage and the machines can't connect? Does the election just stop?

There are some solutions to these issues (cell routers), but then we're just adding complexity to an already complex process. The most secure way I can think of is making a national holiday for voting day, required ID to vote, paper ballots only, restrictions on absentee voting (ban mail in voting altogether except for deployed servicemen), purging the voter rolls every 4 years. When you count the votes, you have one group count, another group verify the count with a recount team. Discrepancies over 0.5% triggers an audit automatically. Each group has oversight from Republican/Democrat who can challenge the count process at any time for any vote. It then goes to a third group for review. All counts are then verified, confirmed, and all challenges settled or the vote discarded. Rep/Dem oversight needs to both sign off on the count or needs to be overridden by a 2/3 majority. Places where you can vote should also be restricted to 3-4 places max for large cities. 1-2 for towns. It can create lines. So sad. If you can't wait, you can't vote. No ballots will be counted unless there is oversight from both sides. If there isn't one, it doesn't get unsealed and it doesn't get counted unless both are there, in person, to view the process and are able to see/read the ballot.

You make it a labor intensive task and you do it on purpose. Automation means less oversight and less hands touching it. This is bad. For every person looking at the votes, that's one person that can call out cheating.