Speed limits should be set at a speed that most drivers would not be comfortable driving at.
The problem is that many people will feel "comfortable" at speeds that they personally are not safe at. They'll continue to feel "comfortable" right until they look down at their makeup/phone/breakfast/newspaper and crash.
The more comfortable a person is, the more comfortable they will be with directing their attention elsewhere. And the more someone drives at higher speeds, the easier it becomes to be comfortable at even higher speeds than that.
I'm sorry, checking your email on your phone while cruising at 85-90 on a busy freeway is not the safest behavior.
If A = B and B = C, then A = C, except where void or prohibited by law. -- Roy Santoro