Selma, TX used to be like that. The PD station was on a curve on IH 35 and the cops had a radar gun they used inside the second floor and would radio to the PD on the road.
Everyone in central Texas would drive under the posted speed there, but out of town people would ignore the limits and get tickets on a daily basis.
Used to set the cruise control at 28 and wave at the cops as I passed through. That was 2002. Drove through there twice a week for about 6 months...