This column got interested in self-driving cars back in 2008, for two reasons. One was the success of the Pentagon’s “urban challenge,” won by a team from Carnegie Mellon that created a self-driving Chevy Tahoe and navigated an obstacle course while obeying California traffic laws.

The second reason was George W. Bush’s flip-flop in favor of new fuel-mileage rules, after his own Council of Economic Advisers correctly derided such mandates as ineffectual and wrong-headed. Thanks to the president’s decision, billions would have...