There are anecdotes of Google Maps causing traffic, routing people to dead ends, etc. There was the incident where Google Maps routed a lot of interstate drivers down a dirt road serving a prison. Last week in Oakland, Google routed drivers away from traffic on I-880, onto Embarcadero where the bridge is closed for construction. Last week, Google refused to route me over the open, clear Sonora Pass between Modesto and Bridgeport, giving me instead a 2.5-hour detour via US-50 to South Lake Tahoe.

I'm sure this Waymo project does not take the perfection of Google Maps data as a given.