Electronic voting is a bad idea and I'd be suspicious on anyone trying to promote it. How can you know that even if the source code for the voting machine is open, the voting machine is running the exact same source code? How can you know nobody has tampered the code the instance is running? I'm glad my country is still running on paper ballots and glad we require voter ID.
I agree with you entirely. There is no absolute way that we know of to truly know the code running is the exact code on GitHub. You can fake that it is in many ways, I don't see people running shell commands on the software before and after they vote to make sure it's the correct software. Even IF that software remains uncompromised, who owns the database? Who stops them from- Way too many factors...
How would you know the shell itself, running on the machine you're trying to verify, isn't lying to you?