The point is you are not supposed to speed whether or not you can see the police or a camera.
They wouldn't be allowed to stand at the bottom of a hill holding a large sign stating 'put your foot down and hurry up', and then do you for speeding.
if you want to speed join the west yorshire police,
speed cameras caught 437 police drivers over the speed limit. ONLY 29 had to pay a �60 fine ( last 2 years )
In Swansea the police speed quite often without blue lights on. They park on pavements and generally ignore traffic laws.
In the last two years I have seen a police driver on a mobile (not the internal radio) with the phone in the left hand but placed against the right ear; and a police driver drinking from a water bottle; both instances whilst the car was moving at speed.
giving people the opportunity to see them and slow down...until well past them...only yo then speed up again... would be pretty pointless wouldn't it...?
it always amazes me how people seem to get angry at the police for trying to catch them doing something they shouldnt be doing!