And how can you trace how people voted. Know why Russia always vote for thieves and tyrants? Because there is no control on the elections and the people vote for money. You want to this situation was in America?
The votes can be traced, as they leave a paper trail every time someone cast their choice. These paper-trails can be matched with the actual results, to check whether any hacking has occurred.
In Russia it is always Putin to win the elections using ballot box stuffing. How can you prove it? Same thing in America. Such elections had never been. The Americans were not ready.