While reflecting on several other threads in wholesys recently, and formulating a response, I started using the 'starship earth' approach. I don't claim any originality, I think Bucky said this some time ago, but I was struck by how useful an analogy it was. For example, starship earth has different decks.
People can move between decks.
Some of the people don't know there are other decks there. See 'The gods must be crazy' movie for depiction of a culture that didn't know there were all these other 'decks' there. Different decks have different capabilities such as communications, transport, instrumentation, supplies, services etc. The crew tends to have some of the same needs however. Regardless of deck.