See, it's interesting on this thread, there's a handful of topics about what should and shouldn't be taught, or how things are taught, and even all as adults there's not one complete agreement on anything. So it's no wonder that schools find this stuff complicated to structure or decide what needs to be taught.
It's almost as though the profession of teaching (or indeed, any job that involves the structure and process of education) is completely and shamefully undervalued in this country...