This is in my opinion, a solved problem. Us Brits have numerous rules around how paper ballots are marked & counted, for example - https://www.theguardian.com/p

This is in my opinion, a solved problem. Us Brits have numerous rules around how paper ballots are marked & counted, for example - https://www.theguardian.com/politics/2015/may/06/vote-with-a-smiley-face-electoral-guide-says-x-doesnt-have-to-mark-the-spot https://www.theguardian.com/politics/2015/may/06/vote-with-a... The fact is, in any election, you only get a few people marking papers like this. At the final local counts, the total spoiled, unmarked, etc. ballot counts are read out as separate totals. Very rarely is this total a number that has any affect on the overall outcome. Average rejection rate of ballot papers is around 0.28%. In those rare instances where it's that close to matter, there would be recounts & additional checks against those spoiled ballots. As a side note, it baffles me that any country would ever not have simple paper ballots with pens/pencils. Pens are safest IMO & pencils should probably be discouraged, I don't personally agree with the (generally historic) reasons for pencils being preferred.