40K is a collection of stolen concepts, and the division of citizens/non-citizens is not new in the sci-fi world.
Take Heinlein's Starship Troopers for example, where cervice in the military would guarantee Citizenship. There were other ways, but for most people such a Tour of Duty was the safest bet to achieve Citizen status, with the privileges afforded that rank.
Why are only citizens allowed to vote?
Student: It's a reward. Something the federation gives you for doing federal service.
Jean Rasczak: No. Something given has no basis in value. When you vote, you are exercising political authority, you're using force. And force, my friends, is violence. The supreme authority from which all other authorities are derived.
Tarald - The Dark Lord of Smeg
You're not drunk if you can lie on the floor without holding on
Gerrymandering could be something like cutting a planet apart so to speak, and rahter than having a central autority (planetary guv'ner) the world is rules by numerous nation-state like us, just that imperial dealings are "let the best nation-state win" deal
My Dark Heresy Game