Let me try this again.

Piss poor parenting most certainly IS at the root of the problem.....I agree. Getting parents to spend the necessary TIME with their kids is not always the priority it should be, IMO.

But here's the rub. Those parents who DO a great job raising respectful, well-disciplined, and socially outstanding children get punished by the public school system. Why? Because Johnny-Don't-Care requires too much time every day just to control. And there is no mechanism to remove Johnny from an otherwise great class. Result is no one gets to learn what would have been possible had Johnny not been there. Johnny's fault? NO! It's the damn parents, but regardless the outcome is the same. Only solution is to separate Johnny from those who want the challenge of learning and put the disruptor where his/her distractions don't affect others.
BTW, it's not the teacher's fault, either....as they are crippled by a system which is impossible to beat. They can't teach and move on until Johnny "gets it". And the result is everyone else in class really "gets it".

So the problem, IMO is the "SYSTEM"
We need to give up the idea of saving them all.