None of the people who had survived ten years of nuclear clouds, acid rain, mutant beasts, radiation diseases, and brutal cannibalism were idiots.
Everybody knew that there were two worlds above the ground and below the ground. The nobles and magnates who initiated the nuclear war, after turning the surface of the earth into a wasteland, hid themselves in the underground metropolises with all the wealth that they had exploited and looted. There, they enjoyed life. There was luxury and prosperity. There were even rivers and willow trees. As Boss Gold Tooth had said, everything was available. It was a paradise below the ground!
The descendants of the civilians, on the other hand, suffered from radiation, corrosion, and internal strife in the desert. They were called 'demons' and lived in hell under the scorching sun.