"Another place the radar is invaluable? In fog. I drive over the Santa Cruz mountains every day to get home and there often is fog. One day there was a car in front of me that had no back taillights." I bet the driver of that car was just using parking lights. I hate that! People who drive with parking lights on don't seem to realize the rear running lights are not on, parking lights are not meant to be used when dri…
(Yes, there are cars with true one-sided parking lamps that will only illuminate one side front-and-rear to mark the edge of the car parked closest to the road.)
I suspect what you're actually seeing is drivers using only the daytime running lights. Those do not turn the rear lamps on.