I don't suppose we have what it takes to objectively measure difficulty, but in many cases it is much more complicated.
Let me give some examples from my own personal life.
I installed Linux Mint to my uncle's laptop. He is 60 years old. He never had any problems.
My nephew who is currently 4 year old can open my laptop and navigate to youtube and find his favorite videos without any help. He doesn't even know how to read yet.
I installed Linux Mint to a friend who is currently in his 70s. He always had trouble with Windows. I told him he could call me whenever he had any problems. He never called. I ask him how it is going everytime we meet. He says everything works fine.
I probably helped over 1000 people now with installing Linux Mint. Of Course some people had problems. Especially in Engineering programs which sadly don't work on Linux, even on WINE (like ADAMS and Solidworks). That's why I dual boot to Win7 when I need to use them. But I gave those 3 examples above to show that Linux is not hard anymore. The only problem is with the software developers who don't write for Linux but this is getting better rapidly.