I have no problem with teacher's looking out for themselves - that's how free markets work. But I can determine if my child will do better with a terrible teacher with ten students or  a great one with thirty or if it would be better to hire a tutor for my daughter for calculus while she takes the class online with every student in the country for $30 a month.

Telling parents they can't measure the value of their kids teachers is a non-starter. They can do it and they can do a better job of it than anyone else as long as they have a free market pricing mechanism to help them out. Give kids vouchers to pay their teachers and administrators and we'll figure out very quickly who the best teachers are and how much administrators are worth.