But just as many experienced drivers are capable of deciding that 55/65/70 mph is too fast in fog/driving rain/icy/high traffic volume conditions, they are also capable of deciding that it is unnecessarially slow on an empty highway, on a dry, sunny, Sunday morning, but the power-that-be are most unlikely to take a favourable view of them making the latter judgement. Unfortunately, the law is an ass simply because the is no way to enshrine the concept of good judgement into it.
Unfortunately there is a rather large chunk of the world that thinks they have good judgement when they manifestly do not. Given the occasions where I have been given a Big Ball Of Mud to maintain I'm not entirely certain that I wouldn't be better off if there weren't a lot more people slavishly obeying things like the rules PBP.
I know for certain that I'm better off now that I've forced some people at $WORK to read it :-)