just because someone is good at one thing does not mean they are good at (or care to be good at) another thing. Can most people be educated on $BASIC_SUBJECT? For the most part, yes. Are they interested in doing so? In many cases, no.
Some examples off the top of my head:
A teacher I worked with who previously owned his own business literally thought the screen/monitor of a computer could watch him. Even after going over how computers work, he looked shifty at his computer. He was unconvinced.
A teacher I worked with could not, after multiple sessions of helping her, understand how to sort outlook mail.
A former boss (owned his own business, made great money, very smart) double clicked _everything_, even when single click would work. Was not interested in changing.
A doctor friend using his patient software - if anything went off script, he had to call in someone else to get him back to a known point.
A former math professor neighbor needed to regularly send out mailers. I helped him set up the most simple solution I could come up with for printing the mailing labels. "Here, open the internet, go to this site, log in, and click the save link. Open this other program, import that data. Load your printer and press print." He needed help. Every. Single. Time. While he said he understands that he pays AOL for internet, he said he does not know what that means (this was like 5 years ago, still using AOL?!). Tried to probe his knowledge and help fill gaps. Never happened. If his internet browser icon moved, he could not get on the internet.
I'm a reasonably smart guy. Don't ask me to fix your car. Or paint. I'll make a mess. Also, basic medical/biology goes in one ear and out the other.
My best friend (granted this was back in high school) could not spell "girl" (literally, "hey, how do you spell girl? Uh, girle?") or solve two step algebra equations. But he could rebuild an engine and identify the type of aircraft flying overhead by the sound the engine made. Mechanical genius. Fast forward a few years, and he found out he really likes geology. Suddenly, he is able to write coherent essays and solve advanced chemistry equations. Amazing what _interest_ in something can do.
Any reasonably intelligent person can be taught a lot as long as they are interested. Many people are just not interested in learning new things, especially when it comes to computers.
Now, on the complete flip side, a service clerk I was talking to two days ago likes to scan in 3d wood models, clean them up in vector based image software, move the files to autocad, and use a laser cutter to make the same models out of metal, and uses an older version of Premier to edit drone footage he captures. My mom figured out on her own how to spoof her user agent to access media that was not supposed to be available to her - but still thinks I hacked her phone via an old computer tower of hers that I was unable to fix.