Everything's a societal reason from some angle. We've probably tilted a bit too hard towards college as a universal path, but I think the median college-degree-required job would still tell you that they're trying to find people who value education and learning for its own sake. The best doctors, lawyers, engineers, etc. are the intellectually curious ones who don't see education as a burden.

You went from "median" job/employer to "best" employee in high value/pay/education roles. These best employee's don't want to work in the "median college-degree-required job", they likely have done some significant post-grad studies and have also likely been saddled with more debt thus requiring their high paying career outcome just to avoid collapse of their personal finances.

I think the median 4 year college graduate going after the "median college-degree-required job", did not care much about their studies at all. They slogged through it hung over from the night before. College was a social experience and gave them a sports team to root for on Saturday. It let them extend their childhood and eschew responsibilities for a few more years.

We have this weird cultural thing in the US where we put super high expectations on education systems but we actually don't value education. We value the social clout and whatnot. Public schools are a prime example, parents are the problem. Make your kids do homework! Take away the video games/phone/tablet/wifi/whatever. It translates to college as, do just what is necessary to get a degree. Often the bare minimum, etc. Cheating runs rampant and so on. It manifests itself in so many ways.

This might not apply to many students at ivy and top schools, but I'd argue it's certainly the median for the nation's college students the past few decades.

Then sell it to doctors, lawyers, and engineers. Those fields aren't really the issue.