On top of this, a future where every car on the road is self driving also lends itself to a future where every car is in constant communication with the cars ar

On top of this, a future where every car on the road is self driving also lends itself to a future where every car is in constant communication with the cars around it. A car 10 spaces ahead is slowing down? Your car already knows and is prepared to handle it with grace rather than slamming on brakes. Cars behaving in a predictable and communicable manner, as much as possible, alleviates traffic by a large factor. This is obviously largely ruined by one single human driver acting unpredictably, so it's a very "all or nothing" resolution.