Certainly, modern societies are not necessarily are stringently structured as what is seen in Omelas. A child is not literally locked in a closet with their waste to keep them company. However, the story does work as a metaphor. Le Guin wanted to write of a condition where human suffering is tolerated, almost written off as a requirement, for human happiness. The construction of human happiness coming at the cost of another's was prevalent in Le Guin's mind in examining the condition of the world in the 1970s. Capitalism and the proliferation of wealth in nations created the presence of an underclass of individuals, who suffered brutally while others enjoyed massive wealth. In a globalized world where capitalism has been exported around the world, this condition of being is still present. Many nations today feature areas of opulent wealth and intense material presence next to the most destitute of conditions. The richest and most materially prosperous homes exist adjacent to the epitome of slum life.
This condition of being is what Le Guin articulates in Omelas. In Omelas, the citizens enjoy their lives of opulence, wealth, and joy at the cost of the child's suffering. There is a clear acceptance that one person's happiness exists alongside the suffering of another. Even the individuals who walk away, the ones who don't do anything to change the conditions of what exists, are present today. Individual alienation and apathy to conditions of suffering are present in the modern setting. There is the presence of trade offs, in which individuals accept the institution that perpetuates unfairness and suffering to some while it parcels out happiness to others. While the modern condition is more pliable in its attempt to remedy the pain of individual suffering, I think that one can see the basic configuration that features happiness and suffering as a trade off and living side by side with one another.