As for negotiating salaries, you have that right, too, except that individuals can't negotiate salaries effectively. It takes a group to stand up to management and demand just compensation. Should the teachers in Wisconsin take a 20% cut, some of them will try to leave. In good times, they would leave. Now, with unemployment being acknowledged to be nearly 10% and most likely nearly double that in reality, not many are going to be able to change jobs now.
Is it just that the teacher that DOES put in all those hours outside the classroom and dos succeed with their kids gets the same salary as the one who does not and fails theirs ?
The notion of standing up to the man is foolish in this day and age as laws prevent the abuses that unions were originally formed to address.
Unions are dinosaurs who onl exist still in government as the real world has already noticed that the ice age has killed them.