Indeed...why should the underclasses learn any more than is required for a job at poundland....?
In my own PhD, the knowledge of historical facts was vital to allow me to see connections and to ask the questions required for analytical thinking.
I don't want to use an example from my own field, as I do not wish to out myself - but let's make one up. One reads 'Lucky Jim' and enjoys it. One notices that it was published in 1954. One then recalls, spontaneously, certain national or world events occuring at or just prior to the time of its publication - the ramp-up to Vietnam, the end of rationing in Britain, the McCarthy hearings, Queen Elizabeth's coronation. One might then ask oneself if these events have informed the novel in some way, think it through, and develop a greater understanding of this piece of literature.
Does that matter? Obviously, I think it does. That the enjoyment and understanding of literature (for example) is a major goal of education. No matter what (or if) one needs it to make a living at poundland. Without education for the sake of education, we are lost. And that requires facts sufficient to make us ask the right questions in the first place.
Obviously, if we wish children not to grow up to do anything besides thank christ they've got a job, then no, we don't need any time-consuming facts to slow down their relentless march into the workplace.