This is a really good point. The city of Madison, Wisconsin has a ridiculous team called TEST - Traffic Enforcement Safety Team. Funded with tax dollars from the police department's Field Operations budget, when TEST lays a speed trap, it means they sit one officer in an inconspicuous lawn chair at the end of a straightaway where speeding is common. This officer has a radio and a laser speed measuring device.
They then hide as many as SEVEN squad cars around the corner, completely out of sight. Usually one or two are higher-ranking undercover cars; in Madison, these are usually driven by police sergeants. The lawn chair officer proceeds to laser every car and radios in any going as few as 7-8 miles per hour over the speed limit, where a regular squad pulls out behind that person and pulls them over just around the bend or on a subsequent block so the traffic stop isn't visible to drivers on the straightaway.
This coupled with Madison's artificially low speed limits in many of these places makes for an easy revenue stream, but it can't possibly be a net positive, especially if some of these tickets are fought in court (like the 8mph ones -- hard to argue that 8mph over the already-low limit through a CEMETERY is particularly unsafe.) The court costs, plus officer salaries, plus the fact that while those squads are waiting for speeders the officers and their equipment are not doing productive things like combating the city's growing gang problem can't possibly make the whole thing a useful endeavor. Just one more reason I'm moving elsewhere...
