I think that Jackson is suggesting that there is a social tendency to choose someone to punish and that this process might appear to be random, based on the presence of the lottery. Yet, I don't think that Jackson is suggesting that this is how society should be. Influenced by the Holocaust and the Red Scare that gripped America in the wake of World War II, Jackson understands that there are "witchhunts" in society. She understands that persecution and targeting are a part of fabrics of social tapestries.
When Tessie repeats, "It isn't fair" and "It isn't right," Jackson makes the statement that individuals are targetted and scapegoated in societies. She does not seem to sanction this behavior, as much as repudiate in her story. For Jackson, any targeting of individuals is not random. The use of the lottery is a "random" method, but Jackson is clear about how cruelty and deliberate malice are not random. Rather, such actions are premeditated and have to be rejected in the strongest of terms. Old Man Warner stating with pride and resolution that "There's always been a lottery" can be seen as Jackson's way of suggesting that societies have always functioned in identifying specific individuals to punish. This process might seem random, but it is horrifyingly deliberate and something that must be rejected on as many levels as possible.