Education is basically a really protracted apprenticeship for people under 18.
NO IT'S NOT
Considering education's purpose to be preparing for work is the hallmark of neoliberal dogma.
Well it should be a primary purpose of public education. (The other of course is preparing children to be good citizens when they grow up, something Trump's teachers either never tried to do or failed miserably when it came to him.)
Now sometimes the best way to accomplish those goals is indirectly, which is why the arts should be a part of public education for all students. However, that doesn't mean we should be subsidizing the education of art history majors.
The primary purpose of education is to foster children's cultural, intellectual and moral flourishing and give them the tools they need to become well-rounded individuals as adults capable of making conscientious choices for themselves and the collectivity. Job training is not and should never be the goal. To claim otherwise is to pave the way for Brave New World.
Spoken like a true Alpha minus.
There are many laudable things that it isn't the government's responsibility to pay for because of the simple reason that it can't pay for every laudable thing. The sort of broad education you advocate is very laudable but it is not and never has been something schools could accomplish all by themselves. It takes much more than a school to raise well-rounded young citizens.
Of course it takes more than a school, I'm not saying there's no role for families and local communities. But not every child has a chance to be born in a loving family or among a supportive community, so the school has to be there to provide a baseline of cultural and intellectual development. It's a moral obligation, so whether it's hard or easy to accomplish is irrelevant. If it costs a lot of money then all it means is that the state should either raise taxes or cut back on something else.