Ask HN: Why Isn't Open Source Voting Software Mandated?

Why doesn't the United States (and other democracies) require open source voting software for all elections? Software that can be externally verified and validated and that could reproduce the results of an election (given the voting data set). Why are citizens expected to trust private companies and closed source software to elect officials? All software has bugs. This fact is not disputed. Citizens should have access to inspect the software used during national and state elections. This should be a basic democratic right. Why don't we do this? Why don't people demand it?