We don’t yet know exactly why a group of people very publicly graffitied, smashed, and torched a Waymo car in San Francisco. But we know enough to understand that this is an explosive milestone in the growing, if scattershot, revolt against big tech.We know that self-driving cars are wildly divisive, especially in cities where they’ve begun to share the streets with emergency responders, pedestrians and cyclists. Public confidence in the technology has actually been declining as they’ve rolled o...