People on the left question the motivations of charter schools and people on the right question the motivations of teachers' unions.
People on the left say they don't think standardized tests should be used to judge teachers (a position I agree with), and then they use their results to illustrate that charters don't do better than traditional schools. People on the right want to judge teachers based on the tests, while ignoring the desires and preferences of the students.
People on the left think public education doesn't get enough money and people on the right think it gets too much (reverse this for the military).
But every discussion involves talking past the people who matter most: the students. And no matter which side wins, most of the students are going to lose. Because the paradigm will be the same. Compulsory attendance to memorize mostly arbitrary subjects, at arbitrary rates, with arbitrary goals.
People are fighting fiercely for their ideological teams, ignoring the well-known fact that millions of kids hate school for reasons that cannot be addressed with money.
Charter schools are not the answer to this problem, so long as they embrace the traditional paradigm. And the traditional paradigm will continue so long as most students are not given the freedom to choose what, when, and how they will engage in one of the most profoundly personal endeavors any of us ever undertake: learning.
While not unimportant, disagreements over charter schools, testing, unions, funding, etc., are, in my opinion, distractions from the most enduring problems associated with schooling.