How is there not widespread open source software for voting out there? It seems like this type of problem could be avoided by creating public software.
Because electronic voting is a solution looking for a problem. Paper voting works and has worked for centuries. There's no need to bring apps/smartphones/whatever into this equation.
There should be, but it’s not just a case of “build it and they will come”. The major parties would need to actually use it (in at least a few states) and for that to happen I think it would need some prominent backers (which could be the parties themselves).