I would put it down to culture. Also note that people’s shoulders aren’t touching apart from the group looking over the pier and maybe the men on the bench look

I would put it down to culture. Also note that people’s shoulders aren’t touching apart from the group looking over the pier and maybe the men on the bench looking into the city. I think most of those people are just sitting a normal distance apart, and I would argue that this is basically the correct distance to sit from someone you know (seems to be the case in all the photos) when on a shared surface like a bench. It’s different with chairs because it is harder to shift a small distance and typically chairs cannot be moved so close together without hitting each other or getting fingers trapped in between