Z:gnu-www-ja-free-digital-society--d110c3-But what if the program is fre/en

But what if the program is free software? That means the election authority who owns this voting machine has control over the software in it, so the election authority could rig the election. You can't trust them either. You don't dare trust anybody in voting, and the reason is, there's no way that the voters can verify for themselves that their votes were correctly counted, nor that false votes were not added.