Perhaps under a totalitarian state, the general citizenry are not permitted clothing which might enable them to hide such dangerous things as weapons, printing presses, or a suitcase full of false indentity papers.

In which case, those who enforce the will of the state will be the only people who can wear these clothes. And the public know this. And the secret police know that the public know this. So they wear long clothes to deliberately strike the jaheebies into the hearts of their victims^Wsuspects.

Or maybe it's a status symbol... they simply wear long clothes because they can, and normal mortals can't. A bit like African bureaucrats who insist on having two or more phones on their desk.

Fair enough. And if I'd lived in Nazi-era Germany then I might perfectly well still have that instictive fear of people wearing long coats.

But I've never lived in Germany, or in the Nazi era, let alone both at once, and this is also true of almost everyone else I associate with; out here in the free world we've always been able to wear coats of whatever colour and length we feel like (except in American high schools recently, which also doesn't apply to many of my friends). So I'm sure that isn't the whole story of why we instantly associate long black coats with the Gestapo. I'm still puzzled.

Watching too many episodes of 'Allo 'Allo?

It's not just the clothing, but how it's worn, and how the person moves. You do look quite sinister walking around in that coat...