>

The issue is capitalism.  It doesn't incentivize social needs that don't have enough return.  Education is investment, it doesn't turn a profit, it provides a return.  And it takes over 12 years to start seeing any of it.
​
And in our capitalist system, the return is too long and too little to compete with other investments.  So private capital seeking return doesn't seek to educate, it seeks a quick return speculating or maybe innovation if it can get Uncle Sam to throw it enough bones to make it a sure thing.
​
If we all seek to take more from a system than we provide, the system dies.  Another name for capitalism is parasitism.
The solution that no one wants to hear is a massive increase in the number of teachers and admins working at each school, as well as a large increase in the number of schools themselves, all of which will cost an enormous amount of money that taxpayers will need to foot the bill for. 
You can't maintain effective control of any situation where you're outnumbered 30-1, and as a result of those numbers being so badly skewed at every level (in the classroom, in the hallways, etc), violent behavior is allowed to fester. On top of that, you have to do so much goddamn paperwork to discipline any student at all due to how litigious our society is, so at a very pragmatic level taking any kind of action can be a massive drain on an already strapped resource (the teacher's time/energy). 
Cramming more workers into a situation isn't a guaranteed fix, but at a really basic level, you can't solve a 50-person problem with 5 people.