for waymo itself, you can overfit on 100% of the situations that will be encountered. 49 square miles isnt that large. its the real world outside that which im concerned about its efficacy in. i think if you put a waymo in a small town that no alphabet engineer has ever even heard of, then youll see it fail badly as well.
FSD is a reinforcement learning problem, and we have no good way of training non-simulation algos for that. and a real dynamical driving environment cant be simulated accurately enough