Shadows. Everyone I know who's tried FSD learns very quickly that it's a random chance that the car will see an oncoming shadow (big truck, bridge, tree, etc) a

Shadows. Everyone I know who's tried FSD learns very quickly that it's a random chance that the car will see an oncoming shadow (big truck, bridge, tree, etc) as a wall and either slam on the brakes or swerve. If you have reliable depth information, ala LIDAR, you'll be able to know that there's nothing actually there.