The author is from Germany and still complaining about Americans interacting with each other less in public? I've been to Germany so many times and almost never seen anyone speaking to strangers on trains/buses/trams. Once I was on a train from Cologne to Frankfurt with a colleague and we were talking nonstop. After a while we realized it was just us talking and probably disturbing everyone else!
People go to extreme lengths to avoid talking to strangers on public transport even in developing countries. Earphones are just so effective.
Oh god I love how quiet European trains are. I used to take trains a lot in my childhood and until my 20s in Ukraine. Sometimes trains were buzzing with voices during the day, especially if someone was drinking. Not all rides were like this, of course, but in general I remember a lot of noise. German trains are so soothing in comparison!