She’s laughing at an in-joke with herself about everyone on board;
She’s engrossed in her book;
He has his headphones in, openly staring at each commuter in turn;
All the other men are suited, reading their papers or fumbling with technology that was crafted much later than their fingers stopped working;
There is an amicably animated conversation in French – naturally the phrase “I’m entering the City Loop, I’ll call you back” needs no translation for eavesdroppers.