Uniformity of standards also has something to commend it; I was much taken by the C-Span-televised education testimony presented to the governors' conference some years back. That testimony made the point that although there is a standard corpus of knowledge to be learned--decimals and fractions, whatever--there is not only no uniformity between states but no uniformity even inside a single school in the prioritization of the teaching of those things.Such schools perrenially prove the adage that "If everything is important then nothing is important." Demanding the teaching of everything all the time means the random selection of topics focused on--and without an extraordinary run of luck it means that students will be re-re-taught fractions and never ever taught percentages.
And the point was made that "women and minorities suffer most"--that whatever coherence might exist in a given school district did not avail people who moved repeatedly from one district to another, and that disproportionately happened to low-income kids.
So there is need for a settled way of sequencing things. There is such a thing as a "model law" for state regulation--something which is not mandatory but which is voluntarily adopted by states because it makes sense and there is no overriding rationale to do anything different. There is also such a thing as completely voluntary standards such as Windows, which provides advantages to its adoptees. And it would seem that in a libertarian world McSchools would arise with coherent curricula, perhaps in association with churches.