A Conservation Law for Empathy?

Earlier this week I found myself in Rome in the morning with about 20 minutes to spare. Walking around the neighborhood I was staying in (Trastevere), I came across an elderly nun walking along one of the bigger, and more crowded, streets of Rome. As I waited for her to go through a narrow passage in the sea of people, a young woman pushing a stroller physically nudged her out of the way, using the stroller to deny the physical space in front of and adjacent to the older woman as she overtook her. The nun grimaced but seemed resigned to what happened. I saw this unfold despite having been out for only about ten minutes. In contrast, having walked US streets in San Francisco, Boston, and New York for over twenty years, I don’t recall seeing a similar situation happen even once. It follows that frequentist estimates of such occurrences in American cities and Rome suggest very different underlying distributions.