There is voting fraud, but it's so infrequent that it has never, ever altered a major election. People are taking the corruption of their hick town and translating it into a national crisis without recognizing how much public oversight controls the national situation. The lives of 329,000,000 and trillions of dollars are riding on getting the job done correctly which is why the national oversight is better than in Buttfuck, Alabama.
Example: Do you know why I knew Obama was always an American citizen? Because if he wasn't, the evil witch Hillary would have dug up the dirt and used it against him. She had the resources and the will. She didn't find shit. If she didn't, after the election, the Republicans would have within months. There was nothing to find. Trump was too fucking stupid to understand that truism, but he was mostly showboating anyway with his Birtherism bullshit.
In modern society, meaning post-Watergate, it's been increasingly difficult for anyone to pull the wool over an entire nation's eyes for very long. Too many people looking to fuck each other over for an edge. When it comes to Democrats vs. Republicans, literally billions of dollars worth of resources are being spent to fuck each other over and get an edge. If one side is hiding something, the other side will find it in due time. Secrets are fleeting, military and political secrets are the most fleeting of all. Too many people looking for an edge.
It's this system of viciousness which is why it works for We, the People. Yes, there are downsides. Trump and this conspiracy theory bullshit is a downside. Hopefully, we've hit the end there and will start swinging back toward the center for awhile.