They could save some if they worked hard to forge weapons or go to Bloodhoof City to buy some goods passed down from Twilight City to improve their quality of life.
Standard economic colonization and control.
The underground world could only move according to his rules when all the resources in the underground world depended on Twilight City.
One day, when Richard no longer needed weapons, he would ask those tribal forces to knit thongs. They would all be willing to do so.
The disadvantages of such a rule were obvious. They did not have enough direct control over those forces, and they had to have enough to suppress them.
The cost was low, and Twilight City could enjoy steady benefits without paying any management costs. That was a good thing.
The current rule was more in line with Twilight City rules.