Waymo seems to be doing much better than Uber, so it can't be just about what's possible. Waymo are also doing much more than just deep learning. For example a deep learning algorithm might be good for predicting possible paths of tracked pedestrians, but figuring out whether you will intersect any of those paths is better solved by a different non-learning algorithm.
Waymo almost predates the current deep learning fad.
While I'm sure they have deep learning somewhere in the stack, the core of their algorithm appears to be based on more traditional techniques, with kalman filters being the core.
