The Ones Who Walk Away from Omelas walk away because they do not want to be a party to the terrible crime of scapegoating the one wretched child. They decide that it is not worth it.
The people of Omelas have made a strange bargain. They want eternal peace, so they choose to sacrifice one of their children, whom they keep in a wretched state, locked up and abused. This way, they are able to live perfect lives, always knowing that the child suffers for them.
The people of Omelas accept the sacrifice of the child because it keeps them in their perfect life. The child is the sacrificial lamb. For them to be happy and carefree, the child has to suffer. They all have to learn “acceptance of their helplessness.” However, some do not.
At times one of the adolescent girls or boys who go see the child does not go home to weep or rage, does not, in fact, go home at all.
Older people also sometimes go. One “falls silent for a day or two” and then leaves. They decide not to be party to it anymore. They always go alone. It is an individual decision. They never come back, and “they seem to know where they are going.”
Leaving Omelas is a moral decision. It is a choice to do what is right, instead of what is easy. It is an irreversible choice, and it means severing oneself from the community forever. But who would want to be part of a community like this anyway--to sacrifice one child for the peace of all?