Which sort of exemplifies just how inefficient and student-unfriendly the current education system is, if it doesn't account for an experience that 'most' people will have. That would make it more in need of reform, not less: it's basically just an archaic, useless, and downright damaging time sink that utterly fails at preparing students for the basic foundational courses it professes to teach, let alone anything meaningful. And while there are always those life-changing moments that can't be accounted for, it's currently set up in such a way that an experience that 'most' people will have makes the entire effort wasted.
Even the sorts of universal things that everyone can make use of are taught in such an esoteric way as to be both inflexible and useless, like you mentioned with middle-school algebra above, or things like the scientific method, or critical thinking, or what have you. I feel like I've learned more about the basic foundations of scientific theory from reading paleontology blogs than I have in 12 years of k-12 education. And I know non- native English speakers that write with more clarity than I did after being in the [bleep]ing IB program, because they write fanfiction regularly.
Any system that is less efficient at teaching than fanfiction deserves to be torn down on principle /s
(And yes blah blah blah information age and the practice aspect of writing and hobbyists being able to pursue their interests at their own pace and everything else people are liable to use as counterpoints- yes. That's the point. You learn more about sentence structure and flow and subtext and motivation by actually writing it, not by reading Shakespeare. And learning that Darwin studied finches as the groundwork for the theory of evolution is not nearly as interesting as seeing those ideas in action and applied to real organisms, their evolutionary theories, and their place in the tree of life. The point is that these are all pretty basic things that our current education system is wholly unprepared to teach. )
If I had to point to one overall problem with k-12 education, it's the lack of practice. Too many concepts are taught too quickly and blown off before anyone can get a handle on them. There's a reason programs like Kumon are so popular (and successful). It doesn't even teach as much as it just gets you to practice repetitively until you have a deep understanding of what you're actually doing.
This ties in to your point about FF - people who write it spend a massive amount of time simply writing (practicing), so of course they get better at it.