Because they have other things they need to do, and mastering it may not provide benefits that repay the investment.
I say this as someone who has run Linux on the Desktop for over 20 years. I do not give a crap about knowing the ins and outs of everything on my system. I have zero interest in learning how bluetooth & Wifi & and all of the hundred other subsystems on my computers work. 99% of the time I want to install the OS, and get on with work.
Sometimes that work means getting down and dirty with a subsystem when I want it to do things that isn't on the normal happy path, but the rest of the time, I want Wifi to autoconnect with a saved password and my bluetooth headphones to autoconnect like a normal person and not futz around learning the intricacies of every daemon and config file in the OS.
It's same reason I pay someone else to service my car. I have fully capable of learning to do it, but I don't care. I have better things to do with my time and money, and there's only so many hours in the day.
(Several edits because I misplaced lots of words pre-coffee)
I've also run Linux on the desktop for over 20 years. Knowing everything in the system is probably nearly impossible unless you're a professional sysadm, like people who specialize in what's called devops now. I agree; I don't want to memorize systemd commands or configure WiFi from the command line; there's convenient GUI tools for things now and it's easy to just work on other things. Even as a developer in a Linux-only environment, I let the devops/infrastructure people deal with most problems if I have them, though of course the corporate computing environment is a lot more complex than my home setup.
I disagree about cars though. Back when I had a car, I did my own work, because it took less time and would be done properly. Unless you have a chauffeur or something (or take Uber I guess, but that costs more money), it takes a lot of time to have someone else service your car: you have to drive it to the shop, then sit there for a while until they can get to it, then sit there while they do the work, then sit around a while longer until they can finally check you out (while also trying to upsell you a bunch of crap), then drive home. Then you find out later they messed something up, got grease on your carpet, etc. Even if they fix that, that's even more time you have to spend. It was a lot easier for me to just do it myself. Someone will probably say something about "loaners" here, but that's usually for larger jobs, not just oil changes.
I say this as someone who has run Linux on the Desktop for over 20 years. I do not give a crap about knowing the ins and outs of everything on my system. I have zero interest in learning how bluetooth & Wifi & and all of the hundred other subsystems on my computers work. 99% of the time I want to install the OS, and get on with work.
Sometimes that work means getting down and dirty with a subsystem when I want it to do things that isn't on the normal happy path, but the rest of the time, I want Wifi to autoconnect with a saved password and my bluetooth headphones to autoconnect like a normal person and not futz around learning the intricacies of every daemon and config file in the OS.
It's same reason I pay someone else to service my car. I have fully capable of learning to do it, but I don't care. I have better things to do with my time and money, and there's only so many hours in the day.
(Several edits because I misplaced lots of words pre-coffee)