I know this is quite a bold and generalized statement I am making. But probably that seems that way only because it has been made out of context. So, let me try to put it in context. And may be than I will make that statement again.
Have you ever traveled in normal city bus, or by Volvo city bus ? Or say, by general class of train or by fight ? Did you notice difference in people's behavior in those different way of transportation ? Okay, one obvious difference could be in their look. But lets keep their exterior look keep aside for a time-being. Other than that what difference did you notice ? Well, at least I have noticed this difference in them: as you move from local city bus to flight mode of travel, friendliness and approachability becomes less and less. Have you ever talked with a guy/girl seating next to you in a flight ?? And how many times you have talked with him/her in a train ???
Let me be a bit specific. And give you my example. At least I have never talked with my neighbor in a flight. But for a bus and train mode of travel I have met few very interesting people. Once in a train I had met a guy who was so much talkative and interesting that distance from Ahmedabad to Bangalore had passed as smooth as knife passes through softened butter. That guy talked with me and with other people of my compartment about himself, from childhood till his recent collage time, touching few subjects about vada paav, idly-dosa, mumbai, gujarat, bangalore etc. etc. And as you know I am good listener and I feel like listnening many time, I heard him fully and time passed for me just like that. Not only that, even after our journey had ended he was used to send me an SMS and even he had called me once !! Very nice guy, he was. Only problem was that he was a guy, not a girl :). I wish in my next journey I meet such kind of talkative girl :).
Keeping jokes apart and coming back on the track again. Same is my experience while travelling by bus. Forget about travelling only. Very recently, a UP bhaiya have simply started speaking with me out of nothing. And I really liked it. Because he did not struggle at all to find so called 'topic' to talk about. Usually while talking with few people we need to find third-party-topics to start conversation. What I mean by third-party-topics are topics about indian politics, about Sachin tenduler's century, IPL, rail accident, terrorist, dhirubhai ambani etc etc. Because, few people don't like to talk about themselves or about some thing related to them. Where as that UP bhaiya and my train friend was above that all, they did not need to find topics to keep conversation going. Conversation was simply flowing on its own.
So I say, poor people are more approachable and friendly natured than that of rich people. What do you say? What your experience says ??