SAN FRANCISCO — Living in this city on the cutting edge, I have lately found myself in a game of chicken with cars driven by nothing but artificial intelligence.Waymo robot taxis, owned by the same company as Google, are now everywhere in San Francisco — and they will soon be driving themselves in six U.S. cities. During rush hour each weekday, easily two or three dozen of the white SUVs, loaded up with cameras and spinning sensors, pass by a street near my house....