Ever think about how hard it must be to be a dictator? I mean no one is scared of Fat Stuff alone. You fear the machine behind him. And you have to believe there are people in the machine who would take him out if they thought they could get away with it. Same goes for Sailor Moon sister. She better be pretty ruthless if she expects to take over. Dictatorin' ain't easy.
Your argument is basically if you can't be perfect, don't bother. You're right. Nothing is foolproof. But if two people are wearing a mask, and maintaining distance, and not sneezing, the odds of infection are very small, compared to doing nothing.