One of the most difficult things in looking at education is that it is very hard to establish causal directions. Are bad teachers creating poor educational outcomes or are places with poor educational outcomes so difficult to teach in that the good teachers leave. It's an important question when you consider possible interventions.
This was very clear in these posts by Andrew Gelman and Jonathan Livengood on education and poverty. There is an impressive inverse association between poverty and educational test scores. It's pretty clear that there could be a common cause (i.e. a confounder) or that the direction of the causal association could go in either direction.
However, the policy decisions are very different depending on the causal relations involved. If poor schooling is a cause of poverty then it makes sense to focus massive efforts on educational reform. But if poor educational outcomes are caused by poverty then this suggests a completely different approach. And, of course, finding a confounder is also a key point.
Now, this assumes that all parties are acting in good faith. If there was an interest in keeping outcomes poor in MS and CA (to pick two low performing states) then educational reforms that worsened outcomes might make sense. This would be a good strategy if one wanted to continue to use "poor educational outcomes" as a talking point as reforms take decades to really take effect.
Finally, one has to worry that real issues (poor educational outcomes) might be used to implement ideological views (i.e. a dislike of unions) when such reforms might be orthogonal to the issues at hand. This wastes the effort of reform without addressing the underlying issues.
Now, none of this is to accuse any group of bad faith. But it is important to realize that there are multiple viable hypotheses as to the causes of poor educational outcomes. The state that I am the most interested in is California; they seem to have very poor outcomes for a large state with a diverse (and often knowledge-based) economy. If that is a reflection of resources expended then maybe we need to focus on counter-intuitive approaches (like raising taxes to improve educational funding) if we really want to make a difference.