> Say you're driving down the road and there's a bit of construction, there's a guy holding SLOW/STOP sign directing traffic.

Here's a picture of a guy holding a hexagonal SLOW sign. They are very common. https://nj1015.com/how-slow-should-you-go-through-constructi...

LIDAR cannot tell you what's on that sign. It cannot read any sign, nor any road markings, nor streetlights, blinkers, stop lights, etc. If you believe that cameras are not capable of being used as input due to dynamic range or any other reason, then that's fine, you just believe that self-driving is impossible (lidar or not). But to believe that one can safely drive using nothing but a completely blank and unlabeled 3D scene (ie, LIDAR-only)? That's pretty crazy.

the back of a stop sign is often a slow sign, or a do not enter sign. The same shape of sign, but different meaning from different directions. The slow variant is often held by construction workers, hence the GPs example.