Here's my hypothesis from ignorance: I don't know much about South America but understand that they freeze dry potatoes on high slopes?

Perhaps they dry best in these holes, the community built them together, like building an oven or kiln, the regularity and sections of 50 holes allow to track whose produce is where; and maybe you sell them on at the same time.

Or, how about ice collection - each hole gets filled with water/snow, it freezes, the lumps are the right size for carrying back to an ice hole. Maybe they can slide them down the slope like a historical ice-cube dispenser.