Same here to some degree. My point is we don't really have a coherent, unified culture regarding social conventions such as these, and there really isn't any way we could have that living in a multicultural society. Ideally I'd like to have a culture where we've agreed on things like the conventions for "person does not wish to talk with others", but I find it hard to get much of a rally for this with the overlying political rhetoric surrounding diversity.
The flip side is some people are actually open to talking to people even when reading a book and/or listening to music. Your own subjective preferences don't dictate how others are carrying themselves, do they? It seems so obvious that everyone else should just agree, right?