Earlier this afternoon, I saw a marked car from the Dearborn Police Department operating a speed trap along the Southfield Freeway, but within the Detroit city limits. For the record, it's been years since I've a car from the Detroit Police Department or anyone else issue speeding tickets along that stretch of road.
It's pretty clear that the City of Detroit believes they so much cash that they don't need to worry about the potential revenue from things like traffic tickets. Therefore, the Detroit Police aren't worrying about it.
I have to say, though, that it's nice that the Detroit Police are so neighborly as to let other police departments come into a city overflowing with cash like Detroit it and a little extra make money for themselves.