- it costs too much
- it's ugly
- humans have only vision
TESLA Engineers wanted LIDAR badly, but they have been allowed to use it only on one model.
I think that autonomous driving in all conditions is mostly impossible. It will be widely available in very controlled and predictable conditions (highways, small and perfectly mapped cities etc).
And about Mercedes vs Tesla capabilities, it's mostly marketing... If you're interested I'll find an article that talked about that.