Because voting softwares don't solve any real problem while creating a horde of its own. Voting is a solved problem. Paper ballot is a perfect technology once you introduce optical readers, and when in doubt, you can always re-count everything again. Sneaking in a false vote requires getting past multiple parties watching the ballot box (and each other) 24/7.
In the recent regional election of South Korea, there was a district where the winner won by a single vote. The runner-up appealed the decision, took the ballots to the overseeing committee, and the committee re-examined individual contested ballots and decided one of the ballots previously considered invalid should count for the second person, making it a tie and (according to some tie-breaking rules) changing the winner.[1]
You can't get that kind of transparency with voting software. It's worse in every way.
In the recent regional election of South Korea, there was a district where the winner won by a single vote. The runner-up appealed the decision, took the ballots to the overseeing committee, and the committee re-examined individual contested ballots and decided one of the ballots previously considered invalid should count for the second person, making it a tie and (according to some tie-breaking rules) changing the winner.[1]
You can't get that kind of transparency with voting software. It's worse in every way.
[1] Link (in Korean): http://news.jtbc.joins.com/html/712/NB11663712.html