You forgot the part of the quote that agrees with what you're talking about:
> yet we don't really cut the umbelical cord (grant them autonomy) until they're in their twenties
The problem pointed by GP is that kids are expected to behave responsibly at school (as if it were work), but parents are not giving them enough autonomy in life. Most of them never "become responsible", because they're taught from early age that they shouldn't (and that feeling is reinforced later, when parents call colleges, and the things you talk about). There's a lot of cognitive dissonance there.
> yet we don't really cut the umbelical cord (grant them autonomy) until they're in their twenties
The problem pointed by GP is that kids are expected to behave responsibly at school (as if it were work), but parents are not giving them enough autonomy in life. Most of them never "become responsible", because they're taught from early age that they shouldn't (and that feeling is reinforced later, when parents call colleges, and the things you talk about). There's a lot of cognitive dissonance there.