There once was a natural progression where you learned how to use the lawnmower, learned how to start it, where to put the gas, and how to check the oil. Next step was a mini bike, then a dirt bike, then a car,
That depends where they grew up. Not everyone grew up like that. I'll use my father as an example. He was born in 1947 and never had any of that ****. He lived in a area of pa with tiny lawn. Used a motor less push lawn mower, so no "understanding" of an internal combustion engine. No mini bike, no dirt bike and when he finally bought a car he didn't work on it. I'm sure he knew how to put gas in it and check the oil but not much else. Many many kids never experienced that stuff.
Hell many modern cars don't have a dipstick so no more checking the oil. Lol.