It isn't even that. They still need to be trained on the job.
For example:
In my health clinic most of the work done by the employees required a solid 8th grade reading and writing skills and a mastery of 6th or 7th grade arithmetic.
If an applicant for a job in my office merely graduated from high school they did NOT get an interview. Why?...It was because I had wasted far too much time interviewing high school graduates that were nearly illiterate and innumerate. If their application showed some community college courses or graduation from college, they likely had the intelligence and reading and math ability to **begin** the training needed to do the job.
If any applicant had come into my office with a Charles Murray-style credential showing mastery of reading to the 8th grade level and math to the 6th or 7th grade level, I would have given them an interview. I would have know that they had enough of a foundation to begin training.
Everyone, who had not had experience in our field, needed to be **trained**. It didn't matter if they finished 8th grade or graduate school.
By the way....I once hired and trained a homeschooler who was only 14. She was a GREAT employee! She never went to high school or college, but went on to be the manager of a very large and busy health clinic. She literally has made a good career for herself.
http://openjurist.org/515/f2d/86/griggs-v-duke-power-company
This basically made employment skills testing a practice that is risky for employers because it may be perceived as sex, race, national origin or religiously discriminating and open one up for litigation.
Employers still need skilled labor or at least hire people that are trainable, right? So they fell onto higher education to provide them people with the certifications, licenses or degrees that show they have some basic skills in this area or at least an aptitude to learn it. Doesn't mean they know everything, but if you have an engineering degree they know the basic concepts etc and should quickly pick up on what you're teaching them. Meantime a high school degree had also become worthless because of the push to make sure we're ALL winners and we ALL have a chance to own a home (ooops that's the another area where the gubbermint has helped us), I mean have a high school degree. That push simply forced schools to drop their standards to where you have kids graduating today with “basic algebra” (not even algebra I), unable to write one decent sentence etc. When my father graduated from HS in 1961 he actually knew how to read, write, do math (trig was the norm), had a basic science background (today kids in some areas do one year of science where they combine physics and chemistry! You have these make belief science classes like medical biology for kids that can't handle a real biology class so they can get their credits to graduate).......... Many kids graduating from an American HS today can barely read anything difficult or complex, hardly write, never learned to really critically think, are weak in the sciences and math........ Critical thinking as taught in American high schools simply means to question all authority and to turn the world upside down, i.e. attack the Judea Christian value system, protestant work ethic, certain moral ideas, the patriarchal society, American exceptional ism and our own history etc. Real critical thinking comes from understanding the formal logic in an argument, the fallacies that we all fall into from time to time and it requires a certain amount of general background knowledge, all of which our kids lack! Back then the HS diploma meant more not because the expectations in the outside world were lower, but because the standards in the schools were higher.