She didn't have to know anything about linux to use it. The same is true for a lot of people. More so in a corporate environment with dedicated staff to handle the harder problems. Hell, most people in offices could get away with a Chromebook and Office 365 today.
Of course, general use laptops and proper linux support are not things that are very common. That part truly sucks. And, yeah, it's not pre-installed for the most part except for some boutique vendors and a couple Dell offerings.
Aside:
Have had a few looks at System 76 lately. May change out my mid-2014 rmbp next year. Unfortunately it's one of the last systems with NVidia, and the metal 2 support for the 750M doesn't work well at all. I'm also probably going to change my desktop to Linux in a few months. Hackintosh support is all but going away, and although I could change out my GTX 1080 with a next gen Navi for hackintosh, but I just don't want to support the mac platform anymore, and my 1080 has a lot of life left in it.
It only really breaks if you want to customise it (or your hardware is badly supported).
They have the right idea today, embrace server-side Linux with .Net Core, and soon, .Net 5. That's what Linux is primarily intended for, it's a server kernel and where the action is in regards to that ecosystem. There's a reason some of the code in X11 hasn't been touched in 20 years.
Arguably a large part of the reason that Linux isn't used in offices is because MS Office isn't available. Of course it's in Microsoft's interest to keep it that way.