The $25k car is going extinct?

I work on my own cars now (as a hobby really) and one of the reasons the new cars are so expensive is they are much more complicated. A lot of this seems to be over-engineering IMO. This is alluded to in the article, but not explicitly stated.

The cars I work on are from the early 90s and everything is very simple to understand.

e.g. Electronics are normally simple circuits that aren't much more complicated than what you would find in a door bell and finding faults is normally just tracing wires and using a multi-meter. I had issues with the brake lights / reverse lights not working, the issue turned out that the spade like connector in the fuse box was pushed through and was making partial contact. Price to fix this was £0.

EDIT: Just remembered this isn't accurate. I had to buy a new reverse light. The entire reverse light assembly was ~£20. So the price to fix was about £20. The light assembly itself was like a big bicycle light.

My newer car needs a OB-II scanner to diagnose anything with a phone app. While this is arguably quicker it can be misleading. Sometimes it will be telling you that something is malfunctioning but it is really the sensor itself. These sensors are £200-£300 a piece. Replacing 4 glow plug sensors cost me £800. I was paying essentially to make the "you must service your engine" light to go away. There was nothing wrong with engine itself.

Any recommendation how to start learning repairing a car? I have absolutely zero experience. A friend of mine said just learn to change a tyre first and I have been procrastinating since.

I went down this route in the early 2010's. In preparation for an over landing expedition I wanted to have mechanical knowledge to be a sort of "mechanic" on the trip so I bought a bunch of "project cars" and began tinkering. While it WAS a lot of fun and I feel smarter, it was a total waste of time.

To save you all the trouble of all I went through, it was fun debugging mechanical stuff, but ultimately there is no "self-reliant car owner"

It all comes down to tools and parts. You need easy access to a lot of both or else you are limited to extremely ugly temporary fixes which amount to super gluing your engine back together.

On our overland trip, when we had an issue, it turned out impossible to fix without a massive lift and air tools, so all my years prep was essentially reduced to having a few extra words I could tell the actual mechanic capable of performing the fix.

If you still want to go down this route I recommend the book "zen and the art of motorcycle maintenance" and have 4 Saabs you can have lol. I'll even throw in the clutch kit you can't install without a custom Saab tool.