The child is bombarded in a classroom by so many stimuli that learning is difficult at best, and, for many children, impossible. The rest of the school environment is hostile to children, indeed, to life itself. While a substitute teacher in a middle school, I witnessed both the precursors to and the after-effects of a drug buy. I didn't get around the corner fast enough to see the buy itself, but many students were there. They had learned to look the other way.
Schools demand virtually nothing from students.
If, however, Jim doubts it, I challenge him to look at an eighth-grade science book from the late 19th century and compare it to the science books used today. However, the primary reason that many children do not learn in a classroom is that the most important thing they have learned is that learning is unimportant. Any question that strays from the recommended curriculum is often either ignored or shot down. Honest questions or comments that don't fall within the party line can be cause for rude dismissal. I've never forgotten it, even after 38 years.