When we walk down a crowded street, we tend to look straight ahead and avoid making eye contact with other people. It's just like a tunnel vision. We are very insular and adjust our reactions according to the situation. Everyone prefers to look at the floor buttons in a lift, than look around and maybe catch somebody's eye.
Crowded buses and trains make us feel the same way. We bury our faces in a newspaper or a magazine - anything but make contact. Perhaps, if we were to loosen up a bit, we might find other people are actually friendly and worth to know better.
As the song says wisely, people are strange when you're a stranger.
*Στην αρχή το είχα γράψει στα ελληνικά, θέλοντας όμως να κάνω εξάσκηση στα αγγλικά, το μετέφρασα και μου άρεσε πιο πολύ έτσι.*