It's really not surprising.

The most familiar computer to young people, their smartphone, does everything to hide and abstract away the file system and even the fact that it's a computer.

When someone doesn't even realize a concept exists, it shouldn't come as a surprise they will struggle.

More cynicism is warranted here. "Platform companies" like Google and Apple love it when users fail to understand how their devices work, because they get locked-in to the plaftorms. This is the successful end result of a long campaign of deliberate miseducation of users.