Why don't we use the math we learn in school?

People don't use math because... it's only useful if you actually really know it.

"Useful" to me means "Lets you do something you couldn't before with a phone".

Aside from imperial inch fractions(Not a fan of those!), most things require fairly little understanding of fundamentals.

Because most people aren't in tech jobs where they can use it.

I don't have a checkbook or do my own investing. I'm single, and very little math is needed to pick whatever is cheapest, especially when only certain sizes of some things are practical for one person.

CAS systems can do basic algebra, FreeCAD does geometry...

FreeTaxUSA does taxes, I don't have a car to optimize insurance costs for...

It's always pretty cool to see a chance to use math IRL just because it's such an uncommon novelty, but I don't see it very often.

To unlock new capabilities you have to learn all those basics, then move on to learn the advanced stuff that computers can't already do.

It's a pretty long term investment of time. Maybe worth it, but still a lot of work.

I have a different take on this situation (thought it bears some resemblance to "Explanation #2" in the article). My years of experience in maths education has led me to the conclusion that the role of maths, particularly in child education, has, or should have, little-to-nothing to do with maths itself: it is a means unto a different end, and should not be used as the end unto itself.

For example, why do we make (US) high-school students study elementary algebra? You would be hard-pressed to find an application of the quadratic formula in everyday life, and yet I maintain that it, and the course at large, has an important pedagogical role. All pre-collegiate levels of maths education (arguably including elementary calculus, but certainly everything before that) presents the student with increasingly complex situations, the tackling of which requires increasingly complex problem-solving strategies. From this perspective, all levels of maths education are effectively drilling structured logical reasoning, problem decomposition, pattern matching, rule application, abstract thinking, abstract/concrete translation, precise/"technical" communication, etc. Maths simply provides a rather nice vehicle for presenting these concepts in an ordered fashion with natural increases in complexity. I even believe that the introduction of integers to pre-schoolers is a valuable vehicle for introducing causality and linearity of time.

Along the way, there are certainly valuable real-life skills that are clear applications of maths concepts, and I would agree with the article that most maths programs are woefully deficient in really underscoring the value of these applications. The article opens with a comic about needing "two-thirds of three-quarters", but anyone who has ever scaled a recipe, or worked with so-called "bakers percentages" knows that this is far from being simply a theoretical word problem.

As an aside, I spent a number of years teaching elementary arithmetic to adult students (usually in their 50s-60s, and, without a hint of hyperbole, commonly unable to solve "2 + 2" without memorization). My role was to find creative ways of communicating arithmetic concepts to people for whom the traditional approach often failed. This strengthened my belief in the above perspective by providing an interesting corollary: many of these people had come to learn the "maths-adjacent" skills, traditionally taught via maths instruction, in fascinatingly creative ways. If the ordering and equal-spacing of the integers was not something they were able to truly grasp as children, sometimes they would surprise me with their approach to other parts of their lives for which perhaps you and I would have a more "normal" solution to.

but isn't that the case with all instruction, not just maths?

As a counterpoint to your example, I, too, learnt the basics of electronics when I was young - Ohm' laws, Kirchhoff's laws, etc. At the time I found it extremely uninteresting, and I certainly didn't apply it to my everyday life and still mostly don't.

In phys ed. I had to play handball a lot. I never played handball as an adult. Running around a courtyard for 20 minutes? I don't do that, ever -- heck, why don't we teach kids to run behind a bus to catch it, or in a crowded airport to catch a connection? Now that would be usable skills...

History, geography, literature (how often do you find yourself finding all the metaphors in a poem?), most of what we learn at school is not "used", nor is it instructed in relation to another skill or problem. And yet, when the issue comes up, it's always maths that is under scrutiny.

There is a lot to review in the way we educate children, all the way to university. Not everything we teach has to be for utilitarian purpose, and yet we need to find a way to interest the kids into it, which we largely fail, in maths in particular, but in other disciplines too. Some of it is about helping them relate it to their every day lives, and some of it to expand their horizon. It's not easy, we don't do it well, and most suggestions I've seen are mostly cosmetic or superficial, and I'm not smart enough to have come up with anything clever myself either, sadly.

I used quite a bit of high school trigonometry when building new stairs and guardrails for my deck.

I always found the context in which I’m solving a word problem to be the most critical piece to accurately solving it —- and the reason they aren’t that great.

Oh, I’m taking a test it over polynomial expressions —- I already know how I’m going to solve whatever word problems I run across.