@akomni
Everything would has a sign up process
an age requirement is the easiest way to get people mature enough to do the work, this is a fantasy middle age setting, kids aren't kids till they are in their mid 20's and have jobs at young ages, but that doesn't mean a place that deals with threats and going out into threat areas wants to send sub double digit children in.
As for the theme, if you have an organization and you don't have a digital way to show you did X, then you have a meet up area, and most of the time these places are treated as lodges, if I want to take a guess, the adventures guild is based on irl hunting lodges or big pubs of old.
you are not going to send out a rookie to kill a dragon unless the dragon is an immediate threat and its all hands on deck, the rank system is there specifically for not sending people off to die when they have 0 chance.
Not sure how often you go to a special place, as in a game shop or more nerdy hobbies, have been stopped in game a game shop and quizzed by the 'veteran' about game systems, have watched it happen to others, at a car show have people who know FAR more flex on people who don't. this is common irl, have a friend who did martial arts and the more seasoned practitioners effed with him day one... my friend is also not someone to be effed with so he has an... interesting story to say about that
✓ over-accomplish your quest goal without thinking about common sense
Is really the only one that never makes sense, I mean I get it when you go in and shit hit the fan and you had to, but this mc and so many that have a search ability just decided there's no kill like overkill, the shocked faces when they do this are understandable.