Which seems a good enough reason that we need to add regulation that these vehicles must have multiple redundant sensors that can operate at any permutation of sunlight/night/rain/snow/fog.

Radar can also see at night, but has poor resolution. Sonar is good at looking through fog but may be unreliable at highway speeds. Lidar really seems like the only viable option here. Maybe even lidar + radar.

I think it's interesting that Elon Musk always says we don't need lidar because it's a visual world. Lidar is a visual sensor. Just an active one.