This wasn't a hard case that needed advanced AI. This was a clearly visible stationary obstacle on a good freeway on a clear California day.
determining the path of travel through lanes markings that suddenly fade out while moving in 70mph on a busy freeway requires advanced AI
its pretty clear the self-driving gods are not giving these cars a grounds up understanding of physics and self-preservation. They best thing they come up with is programmed to drive X mph and to respond probabilistically to a large but finite set of training input scenarios.
Tesla is relying upon advanced AI to do things that its sensors can't do reliably. Its only Tesla who is trying to make self-driving cars off of cameras and inaccurate radar alone.
Maybe Lidar really is too expensive for mass-market adoption. But its the most obvious solution to the problem right now, instead of trying to solve harder problems (ie: camera recognition of 3d objects over trained neural nets).