“I’m more of a skeptic on driverless cars than most people may be,” Gurley said. “The number of 9s that will be required… for a machine to be out there that weighs three tons at that speed, it would need four nines.” Gurley went on to posit that people will be much less tolerant of a machine driver causing a human death than a human driver, and as a result those vehicles would need to be better than human driver, not just as good.