&gt;<i>If the cars aren&#x27;t parked, they are contributing to congestion. And since commutes aren&#x27;t generally balanced[...] that car is going to be loitering around SF somewhere</i><p>You&#x27;re right, traffic patterns are not balanced, so the cars returning to the hot areas for pickups will not be contributing to the traffic in the most-congested direction.<p>Also, SF already has BART, Caltrain, and SF Muni. I&#x27;m not familiar with the specific history here, but transit and housing are the limiting factors for where people live in the first place, so the number of commuters will expand when capacity increases.  The better question is, what if SF <i>didn&#x27;t</i> build those systems?  It wouldn&#x27;t be San Francisco today minus the trains, it&#x27;d be a totally different San Francisco.  So you can&#x27;t really take the ridership numbers from today as evidence that city couldn&#x27;t cope without trains.<p>Also, this was all happening when self-driving cars were <i>not</i> around the corner.  It&#x27;s a different story today.