Since I wrote the OP in a bullet list format I wanted to reply to clarify some things and expand on more in light of new ideas (many that @kuraiummeiā ended up covering before I could respond anyway!):
Ages: Iād completely forgotten about Palaven year lengths. That kind of twists my ideas about ages, but nonetheless, I also donāt want to limit ideas about turian service to what we consider normal compared to our human ages so Iām reluctant to pin myself down to one idea because I like leaving some things open to sociocultural and biological differences.
That said, if service ends at 30 (from the wiki: Soldiers receive a year of training before being assigned to a field unit; officers train for even longer. Most serve until the age of 30, at which they become part of the Reserves. Even if they suffer injuries preventing front-line service, most do support work behind the lines.) that means theyāre equivalent to our ~36yo in terms of life lived when they leave the service, assuming they judge time the same way if they serve off-planet or on space stations, the Citadel, etc. So thatās our equivalent to 18-36yo, or roughly 20 years, which is a long ass time, even accounting for a species with an average lifespan of 150yrs. I think that turians would be taught/most would believe that if itās in the service of the force, itād be worth it, but it also seems strange to me when in times of peace, the Hierarchy would keep its citizens in mandatory service to turian interests and only turian interests for 15-20yrs, so Iām inclined to think the āmandatory serviceā length is shorter than 30yo, but many tend to stay on by choice.
Also about starting at age 15, Iām mostly fed by my own headcanon with this: even though theyāre our equivalent to 18 they may not go through puberty or adulthood socialization at the same time, rate, or even in the same order as we do as we do (eg some parts of their brains/bodies may mature in different orders than ours, including puberty). I had a lot of early assumptions that turians enter the service at 15 specifically because they arenāt full adults yet, and the Hierarchy takes them that young to shape them at a critical point in their lives. They wouldnāt see it as malicious or brainwashing, just standard. (Iām going out on a limb here, but remembering turians are an apex predator species, the idea of discipline and order at a young age might have been introduced early in their civilizations. Even if youāre a ārulebreakerā like Garrus, itās seen as an expected thing to learn discipline mentally, possibly a mentality starting after the Unification Wars to prevent other civil wars, and then after the turians entered the galactic scene with salarians and asari, for the sake of interracial politics. That the krogan, another apex species (Iām assuming), donāt have a similar system to tame teenage rebellion and channel aggression in a healthy way, is probably another reasons turians see them as barbaric and violent.)
I just did some reading and found this on the wiki: Turians have 27 citizenship tiers, beginning with civilians (client races and children). The initial period of military service is the second tier. Formal citizenship is conferred at the third tier, after boot camp. So ignore what I said above about tiers lol. You only become a legal citizen after boot camp, which is likely at least by the age of 17, depending on your performance. I think I also have to keep in mind that some turians will inevitably fail or perform poorly, and some will exceed and excel faster than others, so ages really matter less than aptitude.
Agreeing with @kuraiummeiĀ above re: C-Sec, that was my thought too. Personally Iām not sure Iād think of Garrus transferring to C-Sec as he would another division of the Hierarchy, since itās not within turian space jurisdiction or Hierarchy law. It might be the same if someone transferred to the force on Palaven though, and C-Sec is almost assuredly a highly respected profession for turians and as of ME1, and primarily turian-run, so I doubt there would be a lot of roadblocks for people wanting to join. If a black ops agent wants to transfer to work on another force outside of Hierarchy jurisdiction (like the STG or asari commandos, or the Alliance when they made the Normandy), Iād assume theyād have to go through a bit more bureaucracy just on account of having on record that one of their agents is no longer within their active forces to confirm itās legit, and not like, some cleverly worded paperwork hiding a mercenary group. But theyād still have to go through less hassle itās a public service position, compared to like if they decide they want to go into retail or become a painter.
Poor performance: That leaves me wondering what happens if someone just⦠doesnāt do well lmao. Surely there are some kids who just arenāt good at following orders, like Garrus, and go against the cultural norm but arenāt violent or inclined to take criminal paths? At some point there may be a discussion likeĀ āOkay, you kind of suck at following orders, so this is your tier, you now have formal approval to go to culinary school or something.ā
Nihlus is a good point. I assumed like Garrus that his performance was so good they found reasons to keep him around, and the reasons to remove him never managed to be enough to outweigh them. But I havenāt given it that much thought.
Vetra and Sid never went through training, which is implied to be because they lived off the grid, though not by choice. So some turian kids still fall between the cracks across the galaxy, though due to Vetraās jobs as a grifter, she ended up learning a lot about, though living on the run/situation to situation probably means sheās more adaptable in combat than most (not all) turians who went through the service. Sid clearly knows very little about combat at all. It also clearly didnāt hinder either of their acceptance into the Initiative, so either people donāt care if you did your service, or Vetra mightāve forged their service documentation⦠yeah, Vetra probably forged their documentation. Stupid question.