Just a few years ago, autonomous driving surged into prominence with a seemingly warlike urgency, as though our very survival depended on our cars’ ability to navigate a roundabout while their occupants scrolled through Twitter or made out in the back seat. In Silicon Valley, carmakers set up labs while Google and Uber hired engineers from universities around the world. Audi, Ford, BMW and Mercedes-Benz pivoted their tech-bragging from the car shows to CES, where they extolled the safety-enhancing virtues of self-driving cars. Insurance companies wrote their own obituaries, as driving yielded to mobility. Millennials shrugged. It was madness.