The slavers get paid on commission, based on the number of wastelanders they bring in, and ac… This is just the races module, NPC's are yet to be adapted.
Although the region's earliest history of slavery since the Great War is unknown, it was well established if even more chaotic by 2250. Even in 2008, Fallout 3 was far from being the best looking game out there. Overhaul of characters in Fallout with new headmeshes, high resolution texture maps and a lot more.
