[johndallman]

Among the reasons that command economies don't work are that humans can't actually make plans of the needed complexity for an entire modern economy, and even if they could, they wouldn't stick to them, preferring to "do things their own way", either for personal advantage or local optimisations that upset the larger plan.

Since Centrum's homeworld was built up after a very destructive war, it seems possible that their economy is very much simpler than that of any normal world, making a planned economy only inefficient rather than disastrous. It also seems possible that they are a sufficiently disciplined culture that they actually will stick to plans. That suggests that the Interworld Service is where they put people who aren't good at conforming.