The cause for our failing education system is on every single level.
1) Parents that use the schools as babysitters, or worse yet, orphanages. The vast majority of parents have abdicated the raising of their children to the state. Very few of them really care if their child is learning. What they care about is if they get good grades. This leads to massive grade inflation as well as heavy pressure on the teachers to avoid conflict by just passing students. Hand in hand with that is that huge numbers of parents (most?) believe that if their kids are getting good grades, that the kids are learning. This belief goes so far as to make parents believe that if they pressure the teacher to give their kid a C instead of an F, then somehow the kid will have magically learned the material. I have actually had parents tell me that their school is obviously good because their kid is getting straight As. These beliefs allow parents to tell themselves that they fulfilled their responsibilities, and if their kid ends up stupid, it isn't their fault.
2) Teachers that are not even smart enough to do basic math. Their own advocacy groups show that they are in the top half of earners in almost every state. Yet, they constantly complain that they are in poverty. They don't seem to be able to do the math that shows they are well above average on an hourly scale. They also lie (even to themselves) about the number of hours worked. I have known many teachers, and none of them worked an inordinate number of hours, except for the few language teachers that regularly assigned essays.
Teachers like to talk big about how well educated they are and how they spend 40 hours a week and three months a year outside of school hours to make lesson plans. If they are spending that much time over and over again, they are simply incompetent. With all of that effort, they should also have written plenty of material that buying books would be totally unnecessary.
Right here on on Slashdot, we regularly get stories about how technology doesn't get used well in schools because teachers are unable or unwilling to learn how to use it. These are supposed to be professionals in learning. If they cannot learn better and faster than average, they are obviously unqualified for their jobs.
3) Teachers Unions Teachers Unions are a business. They have to keep teachers dissatisfied with their jobs to stay in business. People in any field that are dissatsified are going to do a worse job. The Unions are one of the biggest factors in making teachers believe that they are underpaid.
4) Administrators that cannot properly run and educational institution. Schools are run as a for profit business. The administrators (with support from the Teachers and Unions) place revenue above education. The fact that a student can pass a class without knowing the material just by showing up so the school can collect money, while a student that takes a three week vacation, but knows the material inside and out fails, shows that education is not the administrations concern.
5) State Politicians take the "not enough money is spent" stance because they can say what everyone knows, without blaming anyone for the problem. The problem being poor education. Here in California, the single largest line item in our state budget is public education, yet we consistantly hear that lack of money is the reason our schools suck. By blaming money, they get to bow to special interest like Teachers Unions, without having to fix the problem.
6) Federal Politicians. While I have not personally heard Obama make any anti-education comments, while Bush was the President Of The United States, he referred to the kids that did well in school as "The Nerd Patrol" in a nationally televised speech.
Each and every one of these groups will point fingers and make the correct statement that it is one of the other groups that is failing in our educational system. Unfortunately, that is a lie of omission. The failure is happening on every level. There is plenty of money being spent on education. That scapegoat is the one thing that isn't the problem. Heck, in my city, there is enough money for one of the local high schools to have a heated pool with an amusement park style water slide, but they still complain that they don't have enough money for books.
To see the general feeling about the purpose of our school system, all you have to do is look at the many debates here on Slashdot (supposedly an intellectual group)about home schooling. The vast majority of posters take the stance that education is at best a secondary role of our school system. That socialization is the primary purpose.
