LIDAR is crucial for self-driving systems to accurately map their surroundings, including things like “how close is this thing to my car” and “is there something behind this obstruction.” The very first Teslas with FSD (and every other self-driving car) used LIDAR, but then Tesla switched to a camera-only FSD implementation as a cost saving measure, which is way less accurate–it’s insanely difficult to accurately map your immediate surroundings bases solely on 2D images.