Why is sameness so important in Jonas' community?
Sameness in The Giver is a means of controlling the people in a few ways. It is human to want to acquire more than you have, and if there are no choices of things to acquire, the temptation should at least theoretically be removed. People who have no reason to strive are far easier to control than those who do strive. You meet their basic needs and they remain content. This sameness eliminates what might be class tensions in a normal society. Everyone, with the exception of the elders, is the same, one class of people who are not competing with one another. Given one class of people who are the same, the governance of the society is far easier, one set of rules for everyone, with a blanket application for all, no need for any judgements or discretion. Sameness makes everyone in the society fungible in most ways, so that any woman can be designated to set up household with any man, and any two children can be chosen to be placed into that household. So there is an ease of administration for the ruling elders. Sameness is also meant to remove envy, which prevents arguments and theft. If everyone has the same possessions, the same sort of housing, and so on, there is no reason to envy anyone else, which keeps resentment and argument down and which removes any motive to take from others. This, too, makes the community easier to rule and control.