The source code is ueless
How do we know that this is the source that was compiled (without being modified) and then run on voting machines? Oh that's right, we don't. This is why a piece of paper and marking an "X" in the circle next to the candidates name is still the best. You can trivially verify that you voted correctly (and the blind/disabled get assistance), and the count is trivial to verify by a human being (watching people count isn't rocket science, and with people from opposing parties and independent scrutineers you can be reasonably sure there is no collusion going on).