G0uli, you seem to be under the impression that police helicopters fly on patrol and / or hover over built up areas as a routine deterrent measure. Perhaps you could add some actual evidence of this.
How do you monitor the effectiveness of a deterrent?
Since NPAS, the days of the local officers in the aircraft knowing when and where activities are likely to take place and being in the air at those times, have gone. Was the ac in a particular area an effective deterrent? ... who knows. Was the aircraft airborne when these local knowledge jobs kicked off? ... for sure.
Of course, positive activities such as this, I would imagine, really only apply to the more urban forces. As for complaints, speaking from an urban unit point of view, flying complaints funnily enough, seem to be another rural thing.
Tr; You're welcome, that was the point of that particular post.