As one of those people who didn’t understand what file systems and directories were at 18, it isn’t taught in early school so you don’t notice it is a thing that exists until you stumble upon it yourself. I distinctly remember the day it clicked and it felt like I had had an epiphany.

Once you break that basic barrier then you rely on your interests to take you further. I went from not understanding that to being a Linux guru in years time, so I fully believe if the desire to learn is there, it will happen. It is just not mandatory to learn anymore. So most people don’t.