You clearly missed the point.

Cybercabs will be on the streets for 15 to 18 hours a day. Private cars aren't on the street for the vast majority of the day.

Cybercabs will be on the streets empty, driving to clean up depots, driving to where algorithms think passengers are more likely, driving to charging and driving to pick up passengers.

The current plan looks like 3-4 legs of Cybercab travel per leg of paying passenger.

Please tell me how this reduces congestion, which was the point, not the total number of cars.