The teaching experience I've had running through how to use applications is almost exactly the same as here. (Though I must say that this is on IO6). Simple things like the way you 'Add' or 'Edit' something being inconsistent really do throw her off. I'm sure anyone who has guided very none-technical people through using technology can relate. It's nothing to do with being 'an idiot'.
There are plenty of older people who take a lot longer to pick up technology like this, and it's also worth noting that as a demographic they are often wealthier than their younger counterparts, and a valuable customer segment.