Originally Posted by Piro21

If the posted speed limits are the safest speed that we should be traveling on our highways, then why don't the police nail everyone exceeding the speed limit at all times? Why then was the speed limit initially set at 115 km/h on these same highways before the gas crisis in the 70s?

The posted speed limit is too low, and drivers realize this, which forces them to rely on their own judgment to find an appropriate speed to travel. If the speed limits truly reflected safe speeds for given roads, drivers would be far more willing to obey them. If it truly were a tradeoff of safety vs a few extra minutes, the vast majority would choose safety, but the inaccurate data supplied by the government and poor driver training skews that choice in most people's heads.