Hi: I'm 87 years old. For half my life I was a freelance professional photographer specializing in coverage of business nd industry. I became a pro in 1950 . I can assure you that the paranoia involving the fear of photography in public spaces existed even then. Although not with the frequency and intensity existing after 9/11. My reaction to being stopped and questioned about being being seen photographing in public areas was not anger but hilarity.
Even as long ago as 1950, the technology for engaging in surreptitious photography was available. Although of course it was not as sophisticated as is it is today. Still, the humor remains. I have always had to ask, why would anyone with malicious intent advertise it by walking around with a big camera stuck to his eye, when a tiny camera that could do the same job could be carried invisibly?
I yet do not understand the reason or the paranoia, but I still have a good laugh when a cop gets all upset about observing public photo activity. Will they never learn?