The world is not as obvious as our eyes may make us think.
So many mysterious facts, distant lands, hidden treasures, fantastic beasts, dangerous people... No government can deal with so many variables, specially when nations are so unstable, divided, unequal. That's a task for specially apt individuals: professional Hunters.
The Hunter Association, a non-governmental organization, is responsible to test anyone who wishes to apply. Those who pass the annual test are granted with their own Hunter license, which gives several benefits, including access to otherwise restricted areas. Besides hunting for whatever their interests are, a Hunter has a duty to protect and preserve world's most valuable treasures, be it a jewel, a species, a city, or even the whole humankind. Of course, every new Hunter must endure some hard training to do so, awakening their own Nen and learning how to use it.
Many Nen-users aren't as well-intentioned as professional Hunters though, and thus may be the main reason why Hunter protection is usually required.
Rodney is a great guy. Oops, nevermind he's a terrible human being.
He likes his sandwiches to be Turkey and Swiss. Triangle cut. Let vern have his crust. Poison the part Rodney eats.
TIB - 2 time award winner "Worst mafia player" at FE (maybe everywhere)