You're assuming that a college degree is a generic item, like, say, a passport. The reason so many Americans have college degrees now is because there are so many shit colleges out there that are essentially teaching remedial and high-school level knowledge. There are for-profit scam colleges like the University of Phoenix. Every town of at least 25,000 people likely has a "community college", and plenty of those are moving to being 4-year institutions that provide degrees of extremely dubious quality. It means nothing to look at the degrees Americans hold. I can state clearly that my parents' generation had a more rigorous high school education than mine did, and from what little I can tell of the educational system today, even less is actually taught, except whatever happens to be on the endless standardized tests that Common Core has brought with it. Almost daily I see articles about people graduating from high school and even college without the most rudimentary skills.
I don't see any "indisputable" evidence of improvement. In fact, I see anecdotal evidence for decline.
ἡ δὲ κἀκ τριῶν τρυπημάτων ἐργαζομένη ἐνεκάλει τῇ φύσει, δυσφορουμένη, ὅτι δὴ μὴ καὶ τοὺς τιτθοὺς αὐτῇ εὐρύτερον ἢ νῦν εἰσι τρυπώη, ὅπως καὶ ἄλλην ἐνταῦθα μίξιν ἐπιτεχνᾶσθαι δυνατὴ εἴη. – Procopius
Ummaka qinnassa nīk!
*MySmiley*