I have noticed similar behavior in the airport itself. I will often find an empty gate area to listen in on a conference call, or just get some work done on my computer. It seems like every time I do this, I will either have someone sit in the seat right behind me - and carry on an overly loud conversation on their phone, or more often, 2 people will sit back there, and converse as if both are hard of hearing.

I have also been sitting in an empty gate and had someone flop down in the seat behind me - headbutting me so hard I saw stars. At least twice. With probably 50 empty seats within 100 feet.

And my personal favorite.... 2 weeks ago I am sitting in a mostly empty gate - my flight doesn't take off for 2 hours. Sitting in one of the middle seats in an empty row of 15 or 20. A "passenger of size" comes along, pushing an old lady in a wheelchair. She parks the wheelchair directly in front of me, facing me, and then sits down in the chair immediately to my left. Well, mostly in the chair. Partly in my chair because she is spilling across the armrest. And she didn't seem to be well acquainted with soap and water. I look around, and in a 30 foot radius, there are only 3 people - Me, trying to concentrate on my conference call, granny - who completely fills my line of sight, and is either trying to have a staring contest or is dead, and my seat buddy - who is taking up a third of my space *and* making my eyes water.... And I put up with it because I keep telling myself that getting up and moving would somehow be perceived as "rude" (by these people that I don't know and will never see again).