A city goes dark, and the smartest cars on the road freeze in place. We unpack the San Francisco blackout that stalled multiple Waymo robotaxis, asking the hard questions about fail‑safes, four‑way stops without signals, and how urban autonomy should behave when infrastructure collapses. We contrast tech stacks and claims across Waymo and Tesla, and we specify what accountability, transparent incident data, and municipal standards should look like if driverless fleets are to share streets with ambulances and school buses.