You still have the sensor challenge either way. Decision-making could be centralized, but that likely requires
everything to follow it - a mix of 50% controlled and 50% human-driven cars would probably be a mess.
I think you sort-of get this, in industrial environments with self-driving transports (both small ones in warehouses and truck-sized ones on mining roads etc). There it's relatively easy to ensure everything is known to central control, access control helps with non-vehicle hazards, ... For public roads, this level of integration seems hard to achieve anytime soon, and would also be a larger trust issue that everything actually supplies accurate data and follows commands. Big standardization effort.
I think there's also been a few public prototypes of self-parking parking garages, but there similar things apply: only for a limited type of vehicle with the necessary support, humans kept out of the building, ...
