Companies are racing to make self-driving cars. But why?

Right now, there are no self-driving cars available for public purchase (even if Tesla misleadingly calls its driver assistance system “Full Self-Driving”). But if and when autonomous vehicles finally arrive en masse, should we cheer, or should we worry? It’s a good time to ask an even more fundamental question: What exactly is the point of self-driving cars? The answer, despite more than $100 billion in investment over the last decade, according to McKinsey, remains surprisingly nebulous. And that should trouble us — a lot.