"Self-driving cars are here," Dmitri Dolgov told the audience at MIT Technology Review's EmTech Digital event this week. It's a matter of how fast we can grow and how fast we can scale this technology in a responsible manner." Waymo's CTO is right: The outfit that started off as Google's self-driving car project is running a limited robotaxi service in the Phoenix metro area. Dolgov also told the audience that the company has tech yet to crack.) GM Cruise plans to launch a service this year. Uber is testing in Pittsburgh. Lyft and Aptiv have a limited self-driving service in Las Vegas. Nuro's delivery bots are hauling groceries around Texas and Arizona. May Mobility is running robo-shuttles in Detroit. So for the public sharing the roads with these things, a few long lurking questions are now more pressing than ever: How do we know these things are safe? And how can the companies that promise they are prove it to us? One thing is for sure: The way we certify human drivers ain't going ...