"Votes went uncounted and no one complained."

Even getting paper ballots right can be a challenge, especially if you aren't particularly motivated to count all the votes.

IEEE Spectrum Online's "The Risk Factor" has a terse summary of a longer article by the Los Angeles Times.

Six years ago, Los Angeles County began using a ballot for nonpartisan voters that had a little-noticed design flaw. Confusion over how to mark the ballot, critics say, caused tens of thousands of votes to go uncounted in three elections between 2002 and 2006.

At the time, election officials knew that some votes were not being counted but saw no need to make changes. After all, the missing votes went unnoticed in the three primary elections and no one complained.