When people talk about self-driving cars, they usually talk about them as though they’re in the future, still a little opaque and unproven. But as so often, the future is already here: it’s just not evenly distributed.For the last few years, Waymo has been operating fully driverless cars in Phoenix and San Francisco. They’re commercially available. Anyone can download the app and hail one: I was recently passing through SF, and took the opportunity to make a few trips by Waymo. I found the exper...