Lidar can't see through fog (or snow/rain to enough of a degree), which is one reason tesla has avoided it. Do you mean radar? In the case of radar, I would hope that it becomes a base features of all cars eventually to avoid/mitigate rear endings by preemptive braking.
If there's a car in front of you, and you're following at normal following distances, it might not be enough. That person will keep going decently fast, and your radar car will follow. The lead car comes to an almost instant stop when it hits, and while radar might pick up the hit, it won't be able to stop as fast as a car hitting a stationary car.
so? With a radar you can follow at a safe distance to brake safely because you can “see” it through the fog. With vision you either slow down to near zero, or follow close enough to see, which doesn’t give you enough time to stop.
