The Mystery of the Aisle Sitters

Can someone explain to me why people do this?! More than ever I am noticing people on the bus sitting on the seat closest to the aisle and leaving an empty seat by the window. It isn’t such an issue when the bus isn’t crowded, but this is becoming one of my pet peeves for my morning commute.

Is it because they are planning to get off at an upcoming stop? That was my initial thought, but more than not I watch these people ride all the way across the park. Is it a fear of windows? This seems like an unlikely answer, but I learned that there are people that have this fear- Defenestraphobia. Or is it simply they don’t want people to sit by them? Maybe, I’m not entirely sure what is going on with the bus riders of New York, but I would love to see this habit fade out!