Are Washington "snipers" rogue cops? Does this explain their amazing getaways?
They are effective in the sense that they deter crime from people who do not want to get caught. Criminals behave differently if they know they are being watched. My neighbor mounted a video camara on his roof after a string of petty thefts from garages, and the crooks moved on. Unknown to the crooks was the fact that the camara did not work and was hooked up to nothing.
The more camaras that go up the less effective they become. There aren't enough bodies to look at all the recordings. The crooks learn to ignore them faster than crows sitting on a scare crow.....and of course they are totally ineffective against criminals that don't care weather they get killed or caught such as terrorists.
You would think that NSA with all their listening capabilities could predict and intervene before every terrorist attack. It just isn't so. I have it from a good source, there are stacks of documents and thousands of hours of recordings that have not been translated from Arabic. You would need more police than people.