Not to mention that when you can't see, you slow down? Does the self-driving system do that sufficiently in low visibility? Clearly not if it hit a pedestrian with enough force to kill them.

The article mentions that Tesla's only use cameras in their system and Musk believes they are enough, because humans only use their eyes. Well firstly, don't you want self-driving systems to be better than humans? Secondly, humans don't just respond to visual cues as a computer would. We also hear and respond to feelings, like the sudden surge of anxiety or fear as our visibility is suddenly reduced at high speed.