> Parking lots essentially switch from random access (which requires expensive unoccupied 'lanes') into a slowly snaking space-filling curve.

Why would they? You still need to get the car to unpark itself when the owner needs it?

Oh, you mean everybody shares cars with everybody? What about letting sections of that "snake" just drive around, stopping at different spots and let people enter and leave? And perhaps let them walk around inside? Congratulations, you've just re-invented public transit.