The most dangerous offenses on the roads are simply not enforced. Politics pressures officers not to cite people for the worst offenses because they are often the ones that people will fight in court and bitch about. Ask anyone who is on the job how popular they would be if they cited people for the following.
Failure to yield to overtaking traffic (keep right except to pass or speeding up to block a pass)
Obstructing the flow of traffic (people doing 10+mph below the posted limits)
Failure to maintain lane discipline (going over the yellow lines into oncoming lanes or violating adjoining lanes)
Failure to display traffic signals
Re-evaluation of license for being too old/feeble or generally incompetent at controlling a vehicle.
All of these are far worse than "speeding" and the politics is not in the favor of an officer who regularly enforces these statutes.
With well over a hundred thousand miles of driving in most of the lower 48, the mid-west highways seem to be the best as far as people driving with common sense. As you approach any city center or the coasts, this all goes to hell fast.
My local area, the damned towns have dropped almost any road that was a 45 limit to 25 now and it is so slow for the road conditions that it just encourages people to text and use the phone and fiddle with the DVD players. It's made things far worse. The limits are so slow that the drivers have even lower awareness for what they are doing...which is supposed to be driving their car.