The checkpoints are often staffed by Uighurs who are complicit in the oppression of their neighbors – there just aren’t enough Han Chinese in Xinjiang to accomplish this kind of artisanal, hand-crafted retail oppression.
It may be more sinister than that. Consider a parallel case:
“The Judenrat constituted a form of self-enforcing intermediary that served the German administration for controlling larger Jewish communities in occupied areas.”
Arendt argues that it wasn’t just a matter of manpower, but much greater efficiency for bringing about the Nazi goals. This is, presumably, one of the main reasons why Eichmann in Jerusalem was such a contentious book.