I can think of a few factors: 1. For any piece of software, a person in the right position should be able to sabotage it. Ken Thompson's Turing acceptance pie

I can think of a few factors: 1. For any piece of software, a person in the right position should be able to sabotage it. Ken Thompson's Turing acceptance piece (Reflections on trusting trust) showed a trivial example of sabotage... 2. It is REALLY difficult to diagnose software while it is running. 3. Risk vs. Reward. Planes have tremendous performance characteristics versus boats or cars. Elevators provide a means for disabled people to get to different levels on a building. But in terms of voting we're trading the security of paper ballots (which humans have spent centuries putting safety measures on ballot stuffing) for convenience. 4. The potential number bad actors with voting is high. While the number of people that want to alter a plane or elevator for nefarious reasons is hopefully limited. 5. Political legitimacy is a very important concept for governments. In democracies, their legitimacy is largely based on ballots. It is really bad for citizens to question the outcome of an election.