Because of fuel burned, brake pads worn, and accidents during traffic on highways and frustration of stopping on a highway for apparently no reason at all.
Wake has enough data on the highway to integrate with auto manufacturers Cruise Control and auto braking function to keep all traffic flowing a almost constant speed. Without the concertina effect caused by human speed adjustment error. Humans will never fully trust or do not want to wait for or would possibly even afford a self driving car.
This system would only be available on highly congested highways to keep the flow of vehicles moving. With this system the more wazers on the highway integrating their speed would be able to preempt average speed allocation for nearly every vehicle.
Less fuel burned, less brake pad wear, less bingles, less frustration for the human race???