It was only car enthusiasts, and more specifically motorheads, that has those skills. Did more older folks know how to work on their cars then today’s youths? Likely

Yes and you are a techie surrounded by techies. You didn't see the millions your own age who used computers in the 80's and 90's without ever understanding them. I ran a mid sized ISP in the mid and late 90's which meant training and supporting the help desk staff to handle the phone calls. I'm very aware of how stupid the average Millenial was about technology. I hired many smart kids. But they were rare. My company had a relationship with a private school where we'd get some high school students to work at my ISP and it counted as their "computer class". There were maybe two kids per class of 100 students each year that knew how a computer worked rather than just how to click the buttons on their Mac or Windows.

There were more computer techies in the 90's. There were more motorheads in the 50's. Computers are more complicated now such that even an average techy can't modify an iPad just like an average person can't fix a car today because of its encapsulation of complications.

Your much older brother is an anomaly. There are exactly 0 people that I know that are 50+ years old that would know anything about fixing a TV.

Wrong generation. I'm 50+ (Gen X) and have no idea about how to fix a TV at the component level. Because I grew up with TV's everywhere like kids today grow up with iphones everywhere.

TV repair was a thing. Radio shack and even Woolworths (Walmart of the 1950's) had a tube tester so that people could walk in with the tube from their TV and test it without paying for professional repair.

Average people knew more about repairing TV's than today!

Again, it's not "everyone". It's the techies of each generation. It's the same subset of the population that has the interest and skills to understand things. The only thing that changes is the popular technology that the techies focus on.