Well, as for the parents abdicating their responsibilities - you do have a point - however, many did not do it. Many had it taken from them. I am one. My children suffered much abuse by a school system because I fought this and tried to get things changed. It was a losing battle. When they have control of your children for the majority of their waking life, they have the upper hand.
As for the children ruining the public schools - that is true - but they will also bring the government to the schools believe me, the government is the one who ruined the public schools. I had children in the public school system for 23 years, I saw it changed and fought it every step of the way - so did a lot of others.
Parent apathy, and parent belief in the system, or just disbelief that in American our children could actually be harmed by our schools, are to blame for much of it. That is exactly the same thing that is to blame for our country's situation. We are either apathetic about the government or we are totally convinced they can cure all our ills. Both things are destructive.
That isn't true.
If you want to get parents involved in education, you give them some control. The current systems does not do that. It gives them some slogans and some pro-formas, but that that is all it does.
A voucher is real power. People will use them wisely.