I'd argue that efficiency in a transport network has to be measured in how many other people and facilities it puts into people's realistic reach. It's a bandwi

I'd argue that efficiency in a transport network has to be measured in how many other people and facilities it puts into people's realistic reach. It's a bandwidth problem only up to a point. Streets aren't all constantly clogged. If you got rid of all powered transport there would be plenty of unused capacity. But many trips would no longer be feasible. Adding public transport helps enormously, but only along popular routes. Self driving cars may not have the density (though, if used exclusively, they could well be an order of magnitude more dense than ordinary cars) but they have the ability to take the most efficient route, and take you there comfortably with significant luggage. That makes trips possible that public transport can't serve.