For example: no homeless. This is all a private territory, and if you don't pay your rent, a guard escorts you off the premises. Very little if any crime because crime prevention is all in one hands and these hands are protecting by and large, their own private property and their profits (because if the crime rate goes up, rent goes down and rent is how they make money).
A wall keeping undesirables out.
Guards/police that can check your papers anytime just simply as they can say in a hotel - "what's your room number"? So no "undocumented" aliens.
There can't be any constitutional etc. bullshit that could prevent them from having an actual 24/7 guarded wall and checkpoints with papers check around their PRIVATE property. It can be a functional society where everyone who's there, belongs there.