We don't have a bottleneck anymore. We have Waymo. They seemed to have solved whatever the issue was...I wonder what the main difference between the Waymo system and the Tesla system is?
The "main difference" is that Waymo wouldn't even try to drive coast to coast.
Because it's geofenced to shit. Restricted entirely to a few select, fully pre-mapped areas. They only recently started trying to add more freeways to the fence.
You're right, they wouldn't try, but I don't think there's any evidence for the idea that Waymo couldn't pull this trip off now from a technical POV. Even if they're pre-mapping, the vehicles still have to react to what's actually around them.
That got us some of the way towards self-driving, but not all the way. AI was the main bottleneck back then. 20 years later, it still is.