Via Bruce Schneier, confirmation of your suspicions about automatic traffic cameras:
Faced with data showing that drivers pay attention to cameras at intersections — resulting in fewer ticketable violations and ever-shrinking revenue from fines — municipalities across the country are reconsidering red light cameras, which often work too well.
Citywide statistics obtained by NBC [Dallas] affiliate KXAS-TV found that red light cameras do reduce accidents. That is a good thing.
But they do it by reducing red light violations, by as much as 29 percent from month to month at particularly busy Dallas intersections. On the face of it, that, too, is a good thing — but not, necessarily, if you rely on traffic fines to make up a healthy chunk of your budget.
I don't even know where to begin. It's just sad, isn't it, that saving lives isn't the reason we enforce traffic regulations.