Actually in snow, fog, rain, and related humans (and cameras) can do pretty reasonably. Things like brake lights and running lights can be pretty severely distorted and you still know the approximate distance to the car in front of you.

Lidar on the other hand is a point source of light (not from the environment) and any distortion makes it less likely for said light to return to the sensor. So with stereo vision (or radar) you can get a relatively accurate distance for a car in front of you. With lidar some fraction of the returns will be bouncing off fog/snow/rain between you and the distant object.

Because of this disadvantage lidar based systems might suggest a slower safe speed, and risk rear ending from humans.