But most people don't consider them comfortable. More the opposite.
But no, the foam and rubber modern "comfortable" shoes are made of are not repairable. Fundamentally, the foam or other sole material simply breaks down. The rubber wears away. And the woven and plastic materials the upper are made of fray, lose padding, and otherwise break down as well.
I have very wide feet, so much so that I've seriously considered manufacturing my own shoes (possibly with a 3D printer). Shoe makers and repair shops do exist but they are becoming quite rare.
My understanding is that a good quality repairable shoe is about $500 or about 5x the price of the $100 shoe we're talking about. Repairing it is labor intensive and adds even more to that cost. So, I can buy at least 5 pairs of $100 shoes for the price of a good quality and repairable shoe and that doesn't consider the repair costs.
I don't think more extensive repairs are economical, and you are better off wearing shoes you like until they disintegrate. There is a bit of mythology about buying expensive boots and repairing them in the hope that it's more economical, but it's really not: https://mastodon.social/@danluu/111068432320682422
I mean if you pay $300 and up for a pair of shoes, it could make sense. If you pay $100 for a pair, you might as well just purchase a new pair. In my case I re-sole the shoes because my shoes fit me well, and they're more on the high-end and thus I've paid a bit for them at the time of purchase. Makes sense for me to re-sole a pair of $1k shoes, rather than purchase a new pair.
To get the prices down, you'd need a lot more cobblers though. And there just aren't many going to trade school for that. It is very much a "artisanal" craft today, akin to tailoring.
These are leather dress shoes though. As far as I know, this doesn't exist in the athletic shoe world. Considering the materials used in athletic shoes, I don't know how a "repairable" athletic shoe could exist without some serious re-engineering.
It goes to show how the big athletic shoe companies are taking the piss. Of course they have middlemen and retailers and whatnot who need to take their cut, but if I can buy a pair of nice leather shoes, made from leather from UK/French/Italian tanneries, with about a million steps done by a human, for the same price as some glued together foam and fabric...something is wrong.