Until a self-driving Uber killed 49-year-old pedestrian Elaine Herzberg im March, autonomous vehicle tech felt like a pure success story. A hot, new space where engineers could shake the world with software, saving lives and banking piles of cash. But after the deadly crash, nagging doubts became questions asked out loud. How exactly do these self-driving things work? How safe are they? And who’s to guarantee that companies building them are being truthful?