I chalk it up to lack of rigor in the elementary/secondary educations.
Both of these statements have merit. My expirience is that teachers lack the background in the subject they're teaching to be able present them rigorously. Math is an excellent example. When a kid asks, honestly or not, "What will I use this for?", most math teachers haven't a clue. "To pass the test" is an incredibly lame sanswer.
There are numerous root causes for the entire problem. Repairing the situation is not going to be an easy process.