I think you overstate how much better mass transit is than self driving cars. Transportation is fundamentally about traversing a graph, and transportation infra

I think you overstate how much better mass transit is than self driving cars. Transportation is fundamentally about traversing a graph, and transportation infrastructure is about maximizing the value of the flows on that graph. Mass transit only makes sense when the edges become a certain weight. The vast majority of point to point connections are far too light to support mass transit. Car transit is a bit better for these P2P and near P2P connections, but still pretty mediocre, because of coordination costs. To a significant extent the issues with mass transit can be remedied by breaking the global graph up into connected subgraphs, and each subgraph can be similarly subdivided, recursively down to the point where the form factors and utilization rates cause the economics to break down. The edges between those subgraphs is mass transit. Autonomous technologies make both point to point and mass transit transportation much cheaper. But labor (market or not) comprises a much more of car transportation costs than mass transit costs. Eliminating that cost inherently drives a shift from mass transit to car transit. Combine that with an efficient coordination algorithm to increase car utilization rates, and it gets a significant upper hand. Each approach will still have its place, of course.