I wonder how this would vary between countries. Generally the cultural norm in the Nordic region isn't positive on striking up conversation with random people; it's seen as a bit of a violation of people's personal space (exceptions apply to bars). There's some kind of joke I don't fully remember about people who start conversations with strangers, which has the punchline: "he's either drunk, insane, or foreign".
The article says that those are "commuter norms" in Chicago also, but my own experience is that Americans are much more likely to strike up a conversation in public, even at places like a bus stop or in a grocery check-out line, which would be considered very weird in Denmark or (especially) Finland. When I lived in Santa Cruz, California, on the other hand, it was seen as a bit weird not to at least exchange a little small-talk in some of those situations.
The article says that those are "commuter norms" in Chicago also, but my own experience is that Americans are much more likely to strike up a conversation in public, even at places like a bus stop or in a grocery check-out line, which would be considered very weird in Denmark or (especially) Finland. When I lived in Santa Cruz, California, on the other hand, it was seen as a bit weird not to at least exchange a little small-talk in some of those situations.