It boggles my mind that any self driving system would knowingly drive into any object, no matter what it is, as large as a police car. I'd be willing to bet that Elon's insistence on only using cameras is combining with the flashing lights to effectively make objects that appear in some frames of video, and not in others, as the camera recovers from the flash... and this makes it appear as noise, and below a certain…
Second, radar wouldn't be better here. Afaik, all of the radar assisted cruise control / emergency braking systems ignore stationary objects when travelling above a certain speed. Using radar, it's difficult to determine the height or shape of a potential obstruction, so a car on the road looks a lot like a metal sign above the roadway.
Lidar is much better, but cost prohibitive to put onto vehicles for driver assistance. A camera system could possibly detect stationary objects of concern, but apparently doesn't.