Many of the most actively involved parents are already removing themselves (and their children) from the public school system, as the payoff to fighting for improvement won't come until after it can benefit their kids. I don't think it's exactly a tragedy of the commons situation, more of the inverse, but the costs (to the parent) are so high that it's hard to blame them. Personally, I think the best we can hope for is that models like Outschool can develop into supplements that work in concert with public school, reducing the relative ROI of going private.