I'd say they have been doing it longer or are familiar with the underlying knowledgebase, so it seems to come easily to them.
Someone who has never used a modern computer before will think that someone who has been learning and adapting since Windows 3.1 would look like a genius. Even if all they know is how to do basic tasks and navigation.
What I have learned to say is "I understand this is new and confusing; however, don't stress out, I was probably more confused than you are when I first learned this." It throws them off a bit, because they think you're the expert, and it clicks that you had to learn it too. If they probe deeper into why it was hard for me, I explain that I'm so used to how things are supposed to work, I have to step back and see how things can work.