The root cause in all of these issues is parenting. If the parents don't bother to care about their kid's education, it's already lost. The education and school system is part of the problem, but you can trace the child's inability to learn back to the parents.
1) Parents dont care about the child's learning
2) The child realizes the parents dont care and so they mess around in class
3) Teacher and school has no authority to really enforce learning. Meaning, you can assign homework, you can punish them for not doing them, but beyond that, you can't force them to sit down to read and learn.
4) Student fails.
5) Parent is up set at the school system so they complain to the principle, and the school district
6) School district pressures principle, principle pressures teacher to water down the curriculum
7) FAILURE of the entire system