WALL STREET JOURNAL: Get the Feeling You’re Being Watched? If You’re Driving, You Just Might Be.

Drivers — many accusing law enforcement of using spy tactics to trap unsuspecting citizens — are fighting back with everything from pick axes to camera-blocking Santa Clauses. They’re moving beyond radar detectors and CB radios to wage their own tech war against detection, using sprays that promise to blur license numbers and Web sites that plot the cameras’ locations and offer tips to beat them.

Cities and states say the devices can improve safety. They also have the added bonus of bringing in revenue in tight times. But critics point to research showing cameras can actually lead to more rear-end accidents because drivers often slam their brakes when they see signs warning them of cameras in the area. Others are angry that the cameras are operated by for-profit companies that typically make around $5,000 per camera each month.

If it weren’t for revenue, they wouldn’t use them. When they say otherwise, it’s an outright lie. If you don’t believe me, try an experiment: Pass a law in which all camera revenues go to the state’s general fund instead of the municipality’s coffers, and then see how many of these get put in place. But even without that experiment, there’s this:

But a study in last month’s Journal of Law and Economics concluded that, as many motorists have long suspected, “governments use traffic tickets as a means of generating revenue.” The authors, Thomas Garrett of the St. Louis Fed and Gary Wagner of the University of Arkansas at Little Rock, studied 14 years of traffic-ticket data from 96 counties in North Carolina. They found that when local-government revenue declines, police issue more tickets in the following year. Officials at the North Carolina Association of Chiefs of Police didn’t respond to requests for comment.

I wonder why not.

UPDATE: Note that once Georgia lengthened yellow-light times, red-light cameras became unprofitable. “The drop in citations is due, in part, to a state law that went into effect Dec. 31 that mandated a one-second addition to the yellow phase at all camera intersections. In January 2008, Lilburn had almost 1,500 citations issued at its three intersections with cameras. In January 2009, that figure plunged to about 300, said Bill Johnsa, Lilburn’s city manager. . . . Since the state law was put into effect, the city’s net revenue on red-light cameras has been reduced to zero or less, Treadway said. The city pays more than $30,000 a month for the service and needs almost 700 citations just to break even, he said.” If all you care about is safety, then, you can accomplish as much by adding a second to the yellow light. If you care about revenue, though, you’ll shorten yellow-light times — as some places have done — even though that’s worse for safety.