The aliens of Trek are insufficiently creative, Sci.
That may be. But the concept of citizenship is a necessary development when you have neighboring polities whose populaces may cross borders and otherwise intermingle -- which is certainly the case for the Star Trek
Universe. You have to have some way to define "ours" and "theirs" when you have separate polities; it's inherent to the definition of a polity.
I agree, but I suggest the concept of "citizenship" for some
alien societies may be no more sophisticated than "same species" or "different species".