I agree, but many college graduates (and for that matter some people with advanced degrees I've run into) have no or little understanding of philosophy/civics, history, literature, etc.
Comparing a college education to K-12 public education doesn't make sense. In general, one needs to understand some mathematics up through Algebra and have some reading and writing abilities to be an employable, productive adult. Whether the public school system in the USA does a good job of providing a basic education is a different discussion.
I’m not the kind of engineer that has a STEM only mindset and I see a lot of value in good Liberal Arts education, but let’s be realistic -- whether it’s because of nature or nurture, there are plenty of college freshmen who are just not going to be intellectuals. Even if it was free (and it would never really be free), it's not a positive thing to encourage them to spend four years majoring in communications or the like.