The only knowledge I distinctly remember gaining in high school was from a class called "consumer auto". I learned to change my oil, replace the brakes and flush the lines, check the fluids, etc.

As a broke college student DIY auto repair was a great way to save money. As someone with a job, it's more of a hobby.

But learning how to fix a basic machine is an amazing lesson in design: you see how mature technology is made to be maintainable, which isn't something you get from a lot of modern electronics.