I find the same in Europe. While I rarely chat for the whole flight, it's rare that I won't at least have a brief conversation with the people around me if I'm on a budget airline (I flew to Iceland last year and had people 2 rows ahead shouting back advice on what to see!). When I fly on the likes of BA however I'm lucky to get an acknowledgement - and even then it's just because they need to move to let me get to my window seat!

I also stay in hostels a lot and often find that the cheaper the hostel is, the more friendly and approachable the people are. Purely anecdotal of course, but there seems to be a pattern based on price. Maybe it's something to do with people on budget airlines being more likely to be an occasional leisure flyer whose excited about their upcoming/finished trip, as opposed to the jaded bunch on here whose always in the air for one reason or another!