Or they're big morons. You can only conclude they have a good reason if you assume it's not an
Idiot Plot, or some other kind of contrived reason.
Oh, I get it - they needed the helmets to work so well, or they'd have no story. They needed for there to be no counter.
It's not even about the specifics - though I still think that their mind reading supercomputer should be able to use optics to recognize someone's wearing a helmet, especially when it can use them to tell people apart.
In the end, it's back to my original complaint: the totalitarian society's failing not because its tyranny brought people to a boiling point, but because it's not totalitarian enough. About it's own survival, too, which you'd think would be the one issue they wouldn't trivialize.