Especially when they only selectively enforce the laws as it is.
It's openly acknowledged in Oregon; it's allowed to exceed the speed limit, if by keeping to the speed limit you would impede traffic; ambient traffic flow is the concept used, so if _everyone_ is travelling five miles over the limit, _no one_ gets ticketed. But this only goes so far, too much above the limit they _will_ ticket you, it's a careful balancing act between the legislated speed, the speed everyone wants to travel, and those who go too far. It's right there in the DMV issued Driver's Manual, the concept of ambient traffic speed overriding obeying the speed limit; too great a difference between your speed and everyone else's speed makes you a traffic hazard. They realized that changing the speed limit to reflect the actual speed driven wouldn't work, people would just go that much faster over the revised speed limit, so they choose to allow ambient traffic flow to override the posted speed limit so long as it didn't exceed the speed limit by too much, the point where they start to call it too much just happens to agree with what the consensus amongst the drivers had settled upon as how much you would push the speed limit; anyone exceeding that consensus gets ticketed, and the amount they are considered to be speeding is computed from the posted speed limit, not ambient traffic flow. It was a very pragmatic reaction to the reality of the situation, and has worked quite successfully for decades now. The actual speed driven is still much lower than before the Feds tied Highway funds to the posted speed limit, accidents are down as a result, and everyone is pretty much content with the situation. No one wants to rock the boat by suggesting revising either the speed limit or the concept of ambient traffic flow.