Gary Wagner, one of my grad school friends who works up the road at the University of Arkansas-Little Rock, was on Fox Business today. He published a nice paper in the Journal of Law and Economics last year coauthored with a WVU classmate of ours, Tom Garrett, a research economist at the St. Louis Fed. The paper explores whether law enforcement officers really do hand out more tickets when local government revenues are otherwise low.
Using annual data for North Carolina counties from 1990 to 2003, they found that significantly more tickets are issued in the year following a decline in revenue. But here's the really interesting part: the issuance of traffic tickets does not decline in years following revenue increases.
So it indeed appears that tickets are used as a revenue‐generation tool, and not just a tool to increase public safety.