The problem is, and will continue to be, teaching is generally treated as a low level job. While the benefits might be good, the pay is extremely low considering all that is asked of them. Your average plumber makes significantly more. The teachers have to worry about pleasing the school board, pleasing the parents, trying to maintain order with children that are increasingly unruly and disrespectful, and trying to make sure their classes meet education requirements that have nothing to do with knowledge and have everything to do with statistics. Is it any surprise the teachers are not exactly a bucket of sunshine?
Before, school funding was always considered a sacred cow. Don't touch it, don't mess with it, leave the schools alone and let them teach. That is no longer true. Education cuts have become the norm. Also, there was a time when the schools themselves had some control over the students. Now there is no discipline of any kind that can be used in the schools without risk of an enraged parent bringing in the lawyers and crying to the tabloids. If a teacher assigns too much homework the parents complain because the teacher expects them to do the job.
Why should the teachers care? They are in a dead-end, low-paying job, that if they stick with it for twenty years will get them up to the very lowest of middle-class incomes. They get nothing but grief from everyone. Either the material is too hard, or not hard enough, or there is too much homework or not enough. Anytime a parent comes to see them, the parent is going to treat the situation, whatever the problem, as if it's the teacher's fault.
When the education system once again becomes important, and when teachers are once again seen as important, you'll get better teachers and better education.