I don't think that's true. Obviously you need elections that can be trusted (and despite everything I don't think elections results are being tampered with too significantly) but if there are bad faith actors (like Trump) then just... Get people not to vote for such an actor. Should be easy enough seeing as they're a bad faith actor right?

Well no, because people are poorly educated or brainwashed or scared or bigoted or hateful or afraid or all the other reasons that people in the US might vote for Trump. The problem is not Trump, the problem is the people voting for him. That's also why shooting him is a bad idea, it only entrenches his supporters even further (aside from the fact that shooting anyone is generally a bad idea).