It's quite interesting to see how individuals behave and socialize within a group of other individuals of no relation to each other. It is quite a different story when individuals interact within a family or circle of close friends and relatives. The major difference is that in a group of non-relatives individuals have expectations of the others that requires reciprocity and equality.
It's no surprise that when someone asks for a favour that they are expected by the other party to return the favour so there are no hard feelings between the two. When a favour is not returned it is easy to understand what happens. The other party feels like they have been taken advantage of which leads to feelings of anger, resentment, and disprespect. It is hard for them to forget what happened to them and it becomes harder for them to give out favours if they feel that they will not get one in return. The person who has not returned the favour most likely has a record of this kind and feels that regardless of hurting feelings they have gained something without giving something. However, within a group, a person with such motives cannot last long without being punished for their actions. Their behaviour can spread throughout the group as they continue to do this to others. They gain a reputation for being stingy and dishonest and eventually cannot gain favours from anyone in the group. The individuals in the group that continue to return favours are the ones to gain more in the end because more people are willing to help due to their reciprocity. This is why most people realize the importance of reciprocity within a group or society because it is a way for them to gain trust and loyalty from non-relatives and maintain good standing.
Perhaps the idea 'be good to thy neighbour' has lasted for so long among societies for the very reason of reciprocity. It really has nothing to do with the mythical belief of karma but instead has to do with fostering bonds between non-relatives in order for there to be reciprocity, especially in times of need. It is not always certain that an individual will be near their family and friends who will help them in any case more or less so it is imperative to have an alliance with others. But good will only come for those who are willing to return the favour or they may end up in the court of law.
Laws are important to have in a society of non-relatives that give and receive favours. In a large society an individual can never be certain if their favour will be returned when they are not familiar with the backgroud and behaviour of the other party. They may pay for a service or make a large purchase on something and never be given what they expected. They may provide a service for someone and never receive payment. There are so many ways in which individuals can be taken advantage of and never see reciprocity in society which is one of the main reasons why there is a justice system. Laws help to maintain reciprocity among socieites of individuals who have no relation to each other. They help to maintain a balance of giving and receiving favours among and between individuals in order for there to be peace and altruisim.
Altruism is an emotion that is innate in human beings and that is why there is recirpocity. An individual may want to help someone in need but would like to know if the other person would do the same for them. It is simple. Or is it? People may want to show altruism to others even if the other party is helpless but they would require some sort of guarantee that there is some sort of benefit for them.
But what happens if the other person cannot return the favour because they are poor or sick or helpless? Does this mean that they are not altruistic or choose to not be altruistic? Where do we draw the line here? In a democratic system of laws and rights how do we help people that cannot return the favour? Some societies around the world are controlled in a dictatorial manner where there are a few individuals who run the show. They take the profits of a working society and divide the funds disproportionately so they get the bulk of the earnings. The rest of society has to settle for their share without question and without fair reciprocity. In other societies people who are in higher income brackets pay more to the government through a tax system. People in the lower income bracket pay less but they also may be entitled to more social services funded solely by the tax system. Although it seems like the higher income earners do not see many direct benefits comapred to the lower income earners but it may be indirectly benefical in that there is added stability in society (i.e. less crime, poverty, and sickness). It is almost always necessary to have some form of a people's government to enforce laws within a judicial system in order to foster reciprocity in a society. In many cases it is the government that becomes the party to only receive favours and brainwash society into believing otherwise. But that is a another story.
Reciprocity is important within a group because it allows non-relatives to be altruistic and respectful to one another. It is hard to know who to trust to return a favour in a society of strangers. But if people who are altruistic teach their children about reciprocity and what it is to be respectful and honest then more people can begin to share this common and innate quality with one another and maintain a 'good' society without all the mythical jargon.