Because the government disappears dissenters.

I don’t really understand why voting machines are complicated enough that there are feasible vulnerabilities. They have one job, and it’s to count. It really shouldn’t be too tough for a crack team of competent devs to write the software required to make them work securely. No network access, a memory safe language, and strict business rules should be relatively trivial to setup. Double that will external audits and you’ve got yourself a stew.