RE: Do we really need to learn this?
I think it's very important not to overlook the fact that there is a difference between passing on knowledge and passing on skills. And also how they fade away depending on how (much) we use them and how much they interest us. Sure I don't remember those matrices, trigonometry, ... but they lay a foundation for further education later on at university. They helped me analyze problems which is a much broader skill than maths alone. Those basic skills helped me learn other skills that are the skills what my boss pays me for.
In my field of interest skills are more important than knowledge. Our IT is evolving so fast that 10 year old knowledge has become obsolete. But that doesn't hold true for everything. Languages, history, ... they involve skill and knowledge.
I always say in school they learn you how to walk and tell you you'll need it to be able to run later on. But maybe you go on and need running to play basketball. But maybe you go iceskating in which case you at least have learned how to keep equilibrum.
We tend to complain too much about our education. We need to remember we're lucky to have such a good one. Lot's of people would literally die for something much worse.
If you use High level math at your job, then you learned it not for nothing, so , good for you. But for many people like me, my husband and the people I know, we don't use this high level math. I am not saying that schools aren't good and that we have to go homeschooling our kids. I am saying that schools can focus on other intersting things because kids can get bored pretty quick and the world isnt just about (high kevel) math. There are also creative people like fashion designers for example who don't use high level math at all or when you have your own business. Intellegence isn't just how good you are in math.