Pittsextra
As for catching criminals as the OP said....catching someone who did over a parking meter for £20 is hardly worth the effort
As I regularly see during the course of my work, police helicopters perform invaluable work helping to protect the community and combat crime (for example) by searching for suspects, helping to apprehend them and assisting with firearms incidents, public order incidents and counter terrorism operations. The noise they create is a trivial price to pay for the enormous value they provide.
Night-time noise would, of course, be significantly reduced if criminals could be persuaded to confine their activities to the day.
The majority of the public are probably not aware of the work done by police helicopters. The whingers probably don't care - provided they aren't the victims of crime.
FL