I don't disagree with your points that politicians aren't always interested in fairness and the money is not allocated equally. 

But by moving to "choice", the imbalance and disparity in both funding and educational outcomes only gets worse, not better. Start taking above average, motivated students and their associated funding out of struggling public schools and those schools will struggle even more.  I'm not willing to sacrifice these kids and the struggling schools. Much better to fix the problems than to create even bigger ones...