So, let’s just forget about the volume of traffic on those limited access highways, and the potential for road hazards (such as a ladder that falls off of a pickup truck). That 16 mph increase does become extremely crucial when there are road hazards (and since no one can predict when something will happen, then if you choose to drive over the posted speed limit the onus is on you if something happens).
Some of the radar detection equipment was permanently installed on an overpass.
And, yes, it was a good revenue maker since they could write multiple tickets for drivers just keeping up with traffic. It was not aimed at the reckless, pass everyone on the road, type of speeder.