I couldn’t imagine such blasé faith in public safety back when I last lived in China, in 2013, but on this visit it was true: Cameras gawked from poles, flashed as we drove through intersections, lingered on faces as we passed through stations or shops. And that was just the most obvious edge of the ubiquitous, multilayered tracking that has come to define life in China. I came away troubled by my time in some of the world’s most-surveilled places — not on China’s account, but because I felt that I’d gotten a taste of our own American future. Wasn’t this, after all, the logical endpoint of an evolution already underway in America?