Your stance of "we don't know, maybe no LIDAR + lots of training data can work just fine" implies that a computer functions as well as a human brain, which as several other commenters have pointed out, is simply not true. I don't have a comment for you about LiDAR on top of humans heads, but I would bet that humans with one eye (and hence no depth perception) are worse at driving than humans with two eyes. There are also countless other sensors in your body that determine depth perception besides just your eyes - your entire nervous system is at play.