Public schools should be cathedrals, places where kids and teacher loves going into. The amount of money we should be pouring into public schools should make all the other counties in the world envy us. Instead we get people wanting to cut school funding and give it to private schools in the way of vouchers. The real reason schools are failing is because we don't care enough about them to give school the funds to make them a success.
We spend more than most other nations per student.
At some point people like you need to realize that the solution involves more than simply throwing money at the public school system. I was in a private school from 1st-8th grades, 1992-2000. My family paid in the vicinity of $5,000 per year for my education, less than the national average during that time (see third chart down). I had a better education than your average public school student. Of course, that means that I was performing at or above grade level, which is more than we can say for a sizable chunk of public school students.
My private education prepared me for a rigorous high school magnet program and from there led to my going to college. Private education works. So long as private schools are accredited and provide the education necessary for their students to lead a successful life, I say leave them alone.