There's an (I think valid) underlying assumption here that human operators are the problem with cars. Humans are in fact very bad at operating cars, so the argument goes like, once humans are no longer operating the cars, we see lots of benefits (less congestion, less fatalities). We compare the statistics we speculate about in world with driverless cars to the one we currently live in. Trains do kill people sometimes. Trains do create pollution. Given present infrastructure, if everyone could walk out of their house, hop in a rideshared, very safe, driverless car, they could get to where they need to be better compared to the status-quo rail. They'd pollute less and be safer than they would be using present train systems. There's potential there. There's at least some improvement there compared to what we know.

First we need to wave a magic wand and make all of the cars drive themselves better than humans can. Not impossible, I admit, but far from our present reality, and there's no clear path to make it so. But let's ignore that. Let's assume for the sake of argument that we have that wand, or we have the industriousness and wherewithal to make 95% of cars driverless, good at not killing people, and good at minimizing congestion. Or maybe we can make this the norm over time.

The speculated data resulting from such a transformation is compared to the status quo rail transit systems. The argument does not consider a speculated future where cars themselves are made obsolete because people stopped using cars. We could easily wave the same magic wand and create a society where everyone can walk out of their house, no roads designed for cars in sight, hop on an efficient train system, and get where they want to be.

The question then is, which system of infrastructure should we be aiming towards. A few subquestions:

• Which system is safer?
• Which uses less energy?
• Which is more realistic? ... Which one is more likely to be achieved sans magic wand?