My mother DOES use Ubuntu, and I've been called about problems 20% less in the past two years compared to previously, with her using Window XP. There's nothing

My mother DOES use Ubuntu, and I've been called about problems 20% less in the past two years compared to previously, with her using Window XP. There's nothing difficult about it - her browser, email, camera and everything work fine. The interface is actually much more simple than Windows. What's the problem?