There's a lot to be said in terms of better UI design. But at some point you really can't eliminate any more: there has to be a baseline of new interactions that someone must learn.
Pushing peddles, turning a wheel, and shifting a stick into different positions didn't have many parallels to real-life actions before the automobile was invented, but people learned that UI regardless.
Because the law requires it, and it requires it because people who can't drive can kill or harm themselves and people around them. If there was absolutely no risk of harming or killing, the law would probably not require training before you can drive. If not being able to use a computer meant killing or harming people, the law would probably require training but because there is no such danger, no one cares and everyone can buy a computer and start using it with no training.
Sure, same for me learning to shift a manual trans four wheeler. But for a huge portion of the population, that's not how their brains work.
I described in detail to my wife how manual transmissions work, she couldn't care less to remember it because she had no direct immediate use for that info so she still doesn't know how to drive one. She's a very smart person but the UI of it doesn't fit her existing knowledge.
Without direct application of provided knowledge, the best way to get someone to remember is to make doing the thing intuitive.
You only have to be trained to learn the execution. Anyone sitting in a car and watching someone drive can figure out what the controls do, it's just that driving a car requires timing.
...of course, perhaps the problem with the above is the assumption that they've had a chance to watch someone drive!
Pushing peddles, turning a wheel, and shifting a stick into different positions didn't have many parallels to real-life actions before the automobile was invented, but people learned that UI regardless.