The famous vocabulary of sociology has “Civil inattention”.

“Civil inattention” is that people pretend to be indifferent in order to spend more comfortably in narrow space like an urban space. It is the social interaction which sociologist Irving Goffman named.

However, Peoples have only pretended to be indifferent. They are not necessarily really indifferent. If a perimeter is surrounded by others, anyone becomes tense.
About the middle of 20th century, People who came to use the train for commuting came to read a newspaper or a book.
The business of newspaper stand or bookstore was produced thanks to that.
A time changes and now, the smart phone is used instead of the newspaper or the book.

By the way, if you take out “Civil inattention” to the collegial examination, it is convenient. Because the student who is not learning the lecture is convinced meaning “not knowing courtesy” and uncommon answers happen in succession.
For example, “Young man of present age does not try to understand the courtesy to the senior at all”. Such points of arguments occur one after another.