Interesting, jaybee. I think that some people derive joy from serving others. Whether in preparing and presenting a fine meal, giving funds to charities, doing charitable work or whatever. Generosity can be so natural to some people that they don't even consider themselves to be generous. Other people simply don't notice what effort is involved all around them to make their lives possible at all. I don't mean misers or greedy people, people who pinch the air when they breathe so that they get a bit more. I mean people who habitually don't notice what other people are really doing, whether at a restaurant or a home, to make a meal possible, let alone delightful. Reciprocity is the response that generous people naturally make. For others it requires an effort. Others try to avoid it. For others, the idea never really occurs. I hope your friends are among these last rather than being aware of avoiding reciprocity.