Not just bigger. Bigger can be fixed with more cpu time. It is a fundimentally different problem. Nobody has a good theoretical answer even with infinite cpu time.

I say this while on a car ferry. Getting on this boat required me to navigate several strange road markings and obey a half-dozen hand gestures from staff, including several that were contrary to the painted lines. No AI is even contemplating car ferries.

It's not just car ferries. Accident scenes and construction zones sometimes require you to obey hand signals and ignore road markings.

There aren't many car ferries around where I live. But there's plenty of construction...

Ever area had its little thing. They may be edge cases individually but edge cases, as a group, must be planned for.

Right. And, sure, that's an edge case for most people. But even if such edge cases only crop up every now and then, you're now at the difference between a reliable automated door-to-door system and one that can drive you around most of the time but every now and then forces a hopefully sober/licensed/competent driver to get behind the wheel to take some actions.

That's a huge difference. Maybe you can address it with some sort of remote OnStar-like system but now you're forcing a remote operator to jump into an unknown context and take actions that were too hard for the AI.

Just need to worry about car Dynamics and pedestrian locations. None of these things can teleport. The problem does have physics imposed limits.