Because the members of the warrior preparation camp needed training, they didn’t need to participate in the manufacturing process. They would occasionally go hunting.
Due to the danger of the wilderness, these warrior trainees obtained little from their hunts. With the small amount obtained, the food was ate only by themselves, and none would be given the people. The reason being they needed to eat meat for training and to grow strength. For the poor plebeians, all they did were handiwork which didn’t exhaust much energy, so grain would suffice for them.