Automotive radars often ignore stationary objects because they have trouble differentiating between a car parked in a lane vs. a car parked on the side of the r

Automotive radars often ignore stationary objects because they have trouble differentiating between a car parked in a lane vs. a car parked on the side of the road vs. an overhead metal road sign. If they didn't ignore stationary objects they would be slamming on the brakes in the middle of the freeway all the time.