a classic market irony example is keyboards.. Every single user here has a keyboard, yet keyboards on a mass scale are cheap and badly designed, with no end in sight.
Anyone who has used a mechanical keyboard can tell you that there is much room for improvement. Rubber dome keyboards are cheap to manufacture and adequate when new but wear out quickly, and most people don't treat them like a wear item. Meanwhile, mechanical keyboards provide a superior typing experience that decreases hand fatigue and can easily last 20+ years with no maintenance.
And don't get me started on layouts. QWERTY is ubiquitous but is a piece of tech debt that has hung around for over a century. Studies have been done and layouts have been produced that are much more efficient and produce less hand fatigue, but none have taken hold because of the sheer momentum that QWERTY has.
Want to see an easy place where there's room for improvement? Why are the rows on every keyboard you've ever used staggered so bizarrely? Because on a typewriter, mechanical limitations meant that there had to be room for the linkages. But inexplicably, we continue to manufacture keyboards that preserve this fossilized layout. Typing on an ortholinear keyboard is sheer bliss in comparison.
I'm curious why. It never occurred to me that this would be a source of discomfort. If I look at how I have my hands on the keyboard, they are angled anyway - my torso is wider than the keyboard center, elbows rest on the arm rests, so the hands then kinda meet in the middle angled. It doesn't look like an orthogonal layout would be particularly advantagenous.
Otherwise, I think keyboards are a case of "good enough" and high transition costs compared to the benefits. I'm a software dev, so certainly above average in the amount of typing I do. But I can't even type with all ten fingers, yet it never seemed like a bottleneck. I can't "outtype" my thought anyway.
I've seen coworkers using 65% or less mechanical keyboards and I have no idea how they get anything done. They always seemed like a cosmetic item to me, though they seem more portable if you're connecting it to a laptop. I use a full mechanical keyboard with keypad and regularly use home, del, pg up/up keys and appreciate having the arrow keys in their own little area. I use a few of the F-keys too. To each their own, but I personally find these tiny keyboards to be far less useful than a full sized keyboard
Another angle for optimization would be QWERTY itself.