>We treat them as adults in school (by making them responsible for their own performance through grading and measuring) from a very young age, yet we don't really cut the umbelical cord (grant them autonomy) until they're in their twenties.
It's inflation, pure and simple. (Alternately, any forced work without reward is called "slavery", and since it's [biologically speaking] totally fine to make slaves of the disenfranchised, that's why we're OK with doing it to children and low-status adults.)
You can't afford autonomy until you're in your mid-twenties even if you actually want it; good jobs for high school students stopped being a thing coincident with the decline of North American manufacturing (both the US and Canada have this problem; Europe's solution is to make everything free but this doesn't solve the motivation problem).
So one of two things have to happen.
Either the education bubble gets popped by some external force (maybe you have to justify spending on a degree to get a loan, or we just ban employers from asking about certifications other than 'has completed Grade 10' unless the job actually requires specialized training, or we start training individuals for trade work much earlier than we do now), or the economy undergoes a rapid expansion (typically a war).
Either of those things will go a long way to fixing society's social media problem: once you have a shortage of manpower, the power of society/employers shrinks and stupid videos captured of you have much less an effect when you are less replaceable. Social authoritarianism always coincides with economic decline- you don't get to infantilize an adult and assume it'll have no effect on their children.