The words "a lot" and "careers" are doing an awful lot of work here. Has anyone quantified this statement beyond looking at job postings for degree requirement

The words "a lot" and "careers" are doing an awful lot of work here. Has anyone quantified this statement beyond looking at job postings for degree requirements? I'm not convinced that actual requirements for a lot of jobs have actually increased in the past 30-40 years, at least not in a way that would be met by a typical 4 year college education. My hypothesis is that employers just started seeing resumes with degrees becoming increasingly common, and just started tossing out those without, similar to what happens with high school diplomas. I'm also not entirely convinced that the "college grad wage premium" is entirely, or even mostly due to having a college degree. I suspect that a significant number of those benefitting from said premium would probably find a way to earn more than the median high school graduate anyway. Granted I am not terribly familiar with research in this particular area, so I'd appreciate a correction if I'm on the wrong track.