I mean, it isn't creepy, it's been a standard for centuries, if you want to vote or be a citizen, you'd need to serve for 2-10 years depending on nation or century, hell, the Romans had a system similar to this but the service required 15 years minimum to 25 years maximum.
Starship Troopers takes place in a post apocalyptic earth, the nation's of the world collapsed due to unlimited democracies and fraudulent Marxian definitions of value which caused civil unrest, this was mainly caused by a pseudo-professional class who called themselves Social Workers and Psychologists, this along with the banning Corporal Punishment ended with societal collapse in Starship Troopers.
After the collapse of national governments, a group of veterans in Aberdeen, Scotland formed a vigilante group to stop rioting and looting.
They hanged a few people, including 2 veterans, and decide to only allow veterans to join their committee due to the mistrust of politicians caused by previous governments.
This contingency plan became routine after a couple of generations, and this group of vigilantes were the start of the Terran Federation.
The Terran Federation is a republic-style parliamentary system that functions as a limited democracy similar to the USA. Full citizenship is not guaranteed to all members of the population and must be earned, typically through military service. Citizenship grants additional civil rights, such as suffrage and the right to run for political office.
The people of the Terran Federation are made up of either "Citizens" or "Civilians".
Everyone is born a "Civilian", and at age 18 every "Civilian" has the right to enroll for a minimal 2 year term of Federal Service, note this isn't a mandatory service, and you can also attain citizenship by performing a valuable service to the Federation, or serving as an experimental subject for a two year term of service.
Note however, you still get all the same rights as everyone else, you can still own property, start businesses and so on, you just cannot vote or run for office.
In theory a completed term of Federal Service ensures a "Citizen" is willing to put the needs of the community before their own personal well-being, this, along with Corporal Punishment ensures corruption is at a minimum.
Personal freedom for all is greatest in history, laws are few, taxes are low, living standards are as high as productivity permits, crime is at its lowest ebb, in all sense the Terran Federation is the most free global state ever envisioned, it's even more free than modern western nations.
And that's because it's Heinlein's Libertarian Utopia.
