I taught SCO Unix before my retirement (2002) and can tell you that students
found it different from the Windows they were familiar with - but not much
harder than the DOS they studied at about the same time. It was all command
line prior to Windows of course and as such required more memorization. Once
they learned to respect case sensitivity and need for the right kind of
slashes and dashes it came well enough.

Today, and ever since Windows 95, the general public has never had to use
the CLI, so the few times that it is beneficial to use it in Linux seem like
an incredible imposition! It's human nature to resist the new and
unfamiliar. We Linux advocates are keeping our brains agile by learning
something new and stretching our few remaining brain cells to the limit.

As one of my former colleagues put it: "Linux isn't an operating system,
it's a way of life".