Regarding the scenario that I've interpreted from the last few posts...the posters are saying a speed trap is an officer issuing citations just past where the speed limit on one section of a road/highway decreases to a lower limit. As in it was 55 mph, then reduces to 45 and the officer writes anybody who is going faster than 45 and is past the 45 mph sign a ticket.
OK, who's gonna step up and tell me just how far past the sign you are legally able to exceed the new limit?...Or (a little easier) how far YOU think it should be?
Ten feet, a hundred, a thousand, a quarter mile? Who's gonna be the one to say..."from this point on, ya gotta be below 45 mph or you really should get a ticket"...who? Speed limit signs are usually 18"x 24"...they can be seen for a lot further distance than it takes to break 10 or even 20 mph.
Concerning the cop backed up in the dark...there is no law that specifies how cops can watch traffic. Heck, it's legal in Alabama for them to use aircraft from 10,000 feet. Cops can used unmarked vehicles, be on foot, or on bikes or motorcycles.
I don't recall anybody posting that they've seen this particular cop come zooming out and after anybody...could be that it's his regular place to stop and catch up on his shift's paperwork. Or maybe he's had some complaints about reckless driving in the area. Or maybe he's eating his lunch in the car instead of at a greasy spoon. Or maybe he was raised in the area and just feels like he's watching over his home. Lots of possiblilities.