I think the real point is that LIDAR has its own shortcomings. Currently the range is too limited, it's sensitive to fog and rain (more than cameras) and it's very expensive. Note that Tesla's for example don't only use cameras, they do have radar and use that to "see" two cars ahead even now. Still they don't use LIDAR and Musk's thesis is that this particular tech isn't needed and overly expensive and cumbersome