By accepting such gifts, you unconsciously accept an unequal deal。Free tastings in supermarkets, tasting-before-buying from street vendors, and forced public gifts from the Krishna Religious Society are all attempts to create a sense of indebtedness。
Even if you used to hate unsolicited sales pitches, once you accept such a seemingly small gift, liking becomes unimportant, and the psychological stress of feeling indebted can greatly increase your chances of compliance。
This is the theory of reciprocity, which is how the Krishna Society just mentioned gained a large number of followers, wealth and assets。The deep reason behind this is actually because in human evolution, those who violate the principle of reciprocity and accept gifts but do not return the good deeds of others are not welcome by social groups。No one wants to be labeled as "ungrateful" or "greedy for petty advantages.。Even, to avoid such labels, people sometimes accept unequal exchanges。