It might be unique to our era (of capitalism), but its definitely true that even if those teenagers appear to be polite, you must remember yourself what it was like to be a teenager, how frustrated and angry and anxious you were all the time, how little you really knew about the world, even if you were nice in public. I don't think those basic impressions you get are definitive.
I don't know how to define 'correctly' here, but in politically and economically advanced countries they develop in much more healthy and productive ways. People who are forced to be adults at 15 often never get a chance to mature.
The operation of such societies should be regarded as an optimization for current circumstances rather than an optimal strategy. If you think what we are doing is poorly suited you are going to have to justify that position on its own merits.
It comes from the same place "scientific" racism did. It's an excuse to not even bother trying because "muh hormones".
Adult initiation rituals tend to be 13-14 in every pre-industrial society (current and historic) because that's when it happens biologically; it is therefore not a surprise, in Western countries where it's delayed by a decade, that the people from 14-25 are not developing correctly.
The first step to fixing this is to acknowledge the problem exists.