It depends, I think. Small kindnesses don't cost much and it's usually just a matter of manners. More significant kindnesses come at some personally cost (time or money). Such kindnesses typically come with strings attached. It may simply be a "thank you", or the expectation may be a similar kindness in the future. They may be doing things for you in order to gain your respect or admiration. I think significant kindnesses with no expectations are rare. An exception to this may be altruism, which is where someone is kind to you because you are facing significant hardships.