User blog comment:PerhapsTheOtherOne/Speculative Spitballing: The General Public/@comment-25555436-20150720171408/@comment-24891101-20150720174433

That is indeed the elephant in the room. I think historically we can attribute it to an aristocracy keeping it arcane knowledge, or simply refusing to initiate (Perhaps in the main only aura may unlock aura?) the common folk, so as to maintain their power base. Users of Aura, then, amounted to knights, and broad parallels could be made to mediaeval European nobility, where in addition to the best gear and training, they are literally superhuman. Hunters proper, meanwhile, could have been varying degrees of apolitical, though of course monarchs would retain the service of similarly-skilled soldiers, and often those would overlap. But it is possible that Hunters formed religious orders, dedicating themselves to purging Grimm and defending all. These remnants of old aristocracy (if even it has passed; in my mind there still remain noble houses in Atlas, though rather reduced in power, similar to the British Peerage, though probably having similar power to the Junkers at the time of the war, if even Atlas were democratic then (or indeed even now)) echo in the emblems and symbols of each individual Hunter, and still in the phenomenon of Hunter dynasties.

But all that is secondary. Why indeed do the presumably vaguely-democratic nations not mandate it as a public health measure? Why does the populace tolerate an elite corps of superhumans? One of the answers may lie in the simple counterquestion of what they would do if such occured. Witness our civilians, who seems rather more durable even without aura than we here on Earth. Jaune's sudden deceleration at the spear of Pyrrha ought to have injured him severely. But it did not. Therefore it may be possible that even those with locked auras may unconsciously call upon it at great need (such as imminent threat to life). Therefore, unlocking aura grants various superpowers, but they are mostly related to combat. Though the various other aspects are nice, their society has no need of extreme strength, durability, or agility in normal life, as it did not need such historically. Just as in modern society few need to run quickly or be physically strong, so too on Remnant. The effortrequired to achieve useful results from aura might also be some degree of prohibitive; if it is somewhat like a muscle, then only through significant training would one get noteworthy results, and would also atrophy through disuse.

Another answer relates back to the state, and rests simply on an extension of the historical reasoning, if a bit more benign: the state shall have a monopoly on force, and it is harder to do so when everyone has superpowers, as the government's edge is blunted.

I will admit that my reasoning here is somewhat less than convincing, even to me, but perhaps it begins to explain the issue. Without a closer look at their society, government, history, and culture, it is difficult to draw conclusions. We shall see.