

Does your assessment assume that you cannot fix it yourself?
Fixing things is nearly always cheaper than buying new unless the base assumption is you cannot perform it yourself and have to rely on a third party.
Repair services are often not even available because the margins would be so low. So, to answer your question of how we got here is because of Capitalism.
Not sure where you’re finding this battery price but I’m guessing it’s much cheaper than that.
I repair just about anything. Sometimes just for the challenge. Electronics are much easier than most realize.
The one thing that causes a barrier for most is the proper tools. “Proprietary” screws are a small toolkit away from just being a regular screw…
You could give the make and model of your laptop and I could send you links to buy anything and everything you need. I’d be willing to bet that tools and parts would be substantially less than buying a new laptop.
Caveat being if it’s a budget bin low spec laptop from a non reputable brand. If it was extremely cheap and cheaply made brand new, I’ll concede your point. Will say it’s still cheaper to fix, but at a certain point it doesn’t make sense to fix something that’s borderline unusable even new (outdated). That is assuming you don’t want to install Linux lol.