Well Patrickt , uniform to me means the same teaching methods and same curricula. The teaching of reading and spelling as you probably know has different approaches some more effective than others .The 'whole ' word or sight reading was in vogue once to the exclusion of the phonetic approach. Syntax was almost disregarded at one point . Some 30 yrs ago primary schools were told to teach maths with the cuisenaire approach .Does anyone remember the boxes of coloured wooden rods of varying lengths in maths classes?
As for history some 'experts' and politicians have had an inordinate influence on what aspects of history are in the syllabus. I could go on ..suffice to say that insisting on the same content and methodology throughout the nation is a bit of a gamble me thinks. I believe there are some States in the U.S. where schools are banned from teaching theory of evolution.
Of course, I remember a lot of the fads in education. And, I remember the test scores dropping to reflect the fads. In my opinion, you should mandate and test the results and not the teaching.