You can drag a file from one folder to another to move it. To the extent that this metaphor works, it's because the little pictures of folders actually remind people of folders, which makes them realize that they can put documents into them. Here's a screenshot from Kai's Photo Soap. It's not very hard. The magnifying glass is a real world metaphor.
People know what they are supposed to do.
And there's no fear that the zoom operation is actually changing the size of the underlying image, since that's not what magnifying glasses do. A metaphor, even an imperfect one, works a lot better than when you don't have one at all. There's no attempt at a metaphor, so it's harder for users to guess how to zoom. But it's a safe bet that more Kai users will be able to zoom in than Word users. A metaphor, badly chosen, is worse than no metaphor at all.