Wait, explain to me how a cop on the side of the road with a radar gun "endangers drivers"? If someone ahead of you slowing down before they get to a cop causes you danger, you were following unjustifiably close.
There are lots of things that can happen on a highway to take a car from 80mph to 0mph in just a few feet (very heavy things to run into) without warning, and if you don't have enough distance to react to that and stop, you are following too close.
Have you never seen how people hit their brakes, swerve into open lanes, and back up traffic for miles just because of a cop or some shit on the side of the road?
There are lots of things that can happen on a highway to take a car from 80mph to 0mph in just a few feet (very heavy things to run into) without warning, and if you don't have enough distance to react to that and stop, you are following too close.