TL;DR: the operating temperature range of these sensors is small, nowhere near automotive spec, and a real problem at high temperatures. Also, watch the fine print on Ouster's thermal specs.

The bigger issue is hot weather; electronics and lasers work well (often more efficiently) at cold temps, and the electrical power running through them self-heats the components. The problem arises when the environment is already hot, and the components still self-heat. This is a particularly large problem for LiDAR, where lasers are very sensitive to temperature and typically use some sort of thermoelectric controller to keep the laser itself at a precise constant temperature. But these thermoelectric devices are inefficient at cooling and lose control (go into thermal runaway) when things get too hot. Automotive component thermal specs (AEC-Q100) require operation (and start-up) at -40C up to anywhere from 70-150C depending on grade. Ouster's -10/-20C to 50C range actually relies on an external base heatsink being used, which they never picture and makes the sensor significantly heavier and larger. These sensors are a far cry from being ready for automotive use.