> I'm also, looking back on a 30 year career, beginning to wonder if a more 'industrial' approach to curriculum design might be useful. Why not simply devise a national curriculum and produce standardised lesson plans and schemes to go with it?

That's what we do in France. In most cases, it works rather well.

The main problem is that it means that every change has to be synchronized nation-wide, which is time and resource consuming. Also, since it's national, it can quickly become a national cause, both for the government (who sometimes decide to change the curriculum for purely political reasons) and for some parts the opposition (« No, that's not how you do Sex Ed! », or such).

Also, we're not too good at handling edge cases (e.g. students with special needs, gifted students, students in places where most parents don't speak French).