We all pay rent to conglomerates to live in underground tunnels, day runners are the underclass, they scout top side for select and necessary items. They die from the heat, quite often.
Diggers are the working class. Expanding the tunnels where the academics say it's safe and possible.
The intellectual elites are geologists and structural engineers and the indoor farming class who fight mass starvation. We try to take spirings and water sources, but they're dangerous to mine around, so we mostly use day runners.
Anyone who is new, and unskilled must work for the colony and sleep nearest the cave mouth.
The elites have artificial sun light and climate control, and first pick of the food. They eat most of the food, actually.
This is our future. Most don't get this far.