Dorsey was on his way to work at Square, the payments company he’d cofounded. Despite his wealth, he always enjoyed taking public transportation to absorb the culture of San Francisco. That morning he noticed that he’d have the whole Route 1 Muni to himself. “A simple morning pleasure: an empty bus,” he posted on Instagram, with a picture of the brown-and-tan seats of the car, unfilled, and not even the driver visible.