The very simple answer to the failure of the school system is this:
The school system in the western, industrialized, world, is based on two ideas which have then given way to horrific corruption.
The first is: everybody is capable of learning. This is true. I genuinely believe far more people are capable of learning given hard work, improved educational technique and better-organized schools. Bell-curve grading will never tell you this, but we have today a greater percentage of technically 'intelligent' or 'gifted' children (not 'geniuses with 200 IQ', but children with an intellectual capacity slightly above what used to be the 'norm') than we had before. However, this has been corrupted in two important ways:
One, intelligence is not permanent. A person can become dumber, or smarter, over the course of their lives. I have seen some truly sad cases of the former and some spectacular incidents of the latter. I am sure so have you.
People take everybody is capable of learning given hard work and transform it into let us just make the exams easier. Why is this? Because the educational system is run – in many, not all, cases – by, and for, educators. Which brings me to the second point:
Public education exists to ease the burden of working parents. Far, far too many parents believe that since 'the school will teach the children', they can just shove their children into the school gate, pick them up eight hours later, and the children will 'learn' by some mysterious process.
The thing is, if you treat people like indolent, irresponsible morons, they will become these morons.
So we have people – at the early college level – who do not know how to write an essay. Or what a paragraph is.
Here is a fact: For civilization to continue to exist, these skills need to be taught in the same way you teach basic science skills. So we will end up teaching them in college. We will take away time from teaching about Jeffersonian-era foreign policy, the Shakespearean sonnets, and other things which are important to the creation of a humanities B.A. and we will have to teach college students what a paragraph is.
Of course, the colleges could shove a stick up their rectums and avoid accepting students who do not know what a paragraph is, and kick people out if they don't. But then [a] The colleges would be bankrupt, and We would have a problem in a few years as nobody would know what a paragraph is.
So, since the basic skills are not taught in school they are taught in college, because someone needs to teach them.