I'm well-educated, reasonably intelligent and can do lots of things but...
I can't operate our new microwave (previous one was OK - just turn the dial!). Husband has had to write out simple bullet-point instructions on a card, because I can't keep the complicated sequence of operations in my mind.
I had to give my little Nespresso machine to my son because, although there were only 3 things you had to do, I couldn't get them in the right order without a list.
I hasten to add that I can play the piano and operate washing machines, dishwashers and vacuum cleaners!
I think it's because I'm what's classified as a 'visual' learner. I learn by reading or seeing a picture - NOT by being shown how, and not by doing things. I know there's an old saying. "To do is to understand", but it doesn't work for me. If someone actively demonstrates something, I always get a piece of paper and write things down - I can't learn or remember from a demo. My daughter is just the opposite - she is a 'doer' and everything is always TLDR for her.
Strange - because most people are the other way around!
I console myself with the fact that some very intelligent people aren't great on a practical level.