"Hirsch advocates a return to a basic "core curriculum", where students are expected to learn western civ and US history, as well as science, on top of the critical skills of reading, writing and mathematics."
This is where we disagree. The curriculum you propose sounds great, but it can never be taught under compulsory requirements, because there are too many special interest groups who will co-opt it for their own use. This is obviously what has happened in the modern educational system.
"While I think K-12 should be compulsory, it needn't be public. "
This is the system we already have and it is failing miserably. A friend of mine was an elementary school principle for over 25 years. His comment to me after he retired was, "You just can't educate 100% of the population". His contention after being on the front lines for many years is that there are some people who just don't want an education, and those people de-value the whole enterprise.
I do agree with your comments that education should be made available to everyone, though. At some point there will have to be a re-thinking of the way education is done in our society but it won't happen anytime soon, simply because too many people make money off of the current system.
As far as "too much curriculum," the WSJ had a fascinating article several years ago that reproduced a test given to students at or about 1900. I am here to tell you, most college grads today could not pass it. It was for admission to high school.
You have a point! At our university, I made a point of getting on our "General Education Committee" which was tasked with creating a new general education "framework". I was hoping to nudge things towards a core-curriculum model. No such luck. Our gen ed requirements are even more nebulous and abstract than before. The model I had in mind is what they have in Texas: all public universities there have a tight core where students are obliged to choose maybe two dozen courses from a list of maybe four dozen. Their requirements include such things as 6 credit hours of US history (or 3 credit hours of US history and 3 credit hours of Texas history). We, on the other hand, have requirements such as "Methods of Inquiry and Investigation in the Social Sciences" which can be met by any of a zillion courses (e.g., you can avoid history if you wish). The Texas system was installed state-wide by the legislature. The professoriate, left to its own devices, will never ever agree to a Texas-style core curriculum.