Fleets of self-driving cars used to be as about as plausible as unicorns jumping over rainbows. But with major automakers and technology companies racing to develop, test, and deploy self-driving cars to the masses, the era of autonomous vehicles suddenly seems believable. It’s possible that today’s 5-year-old will be able to order a self-driving car using an app, assuming that technology continues to progress and the complex web of regulations gets sorted out. And so…