A bigger danger than speeding on clear highways is things like tailgating, weaving between lanes, aggressive passing, and distracted driving. This often happens below speed limits, and is not the focus of automated speed enforcement systems.
In Ontario, Canada, we have wide, well maintained, and well engineered highways that have unreasonably low speed limits of 90 or 100 km/h. While there are times when it’s necessary to drive more slowly (bad weather, traffic ahead), strictly enforcing such limits on wide clear highways in good weather would be silly. People here generally drive 120-130 km/h because cars are designed to operate safely and efficiently at these speeds. Strictly enforcing unreasonably low speed limits would just breed contempt from drivers, so currently the police are lenient with the speeds people actually drive. Strict enforcement of speed limits could be more reasonable if they set realistic speed limits, perhaps variable ones depending on the weather and traffic conditions.