What is an electronic folder structure?

Why does the folder structure for Picasa provide such a frustrating user experience relative to other Google products?

• I quite like many other Google products, but after a few months of use, I still can't figure out how to do quite simple operations in Picasa; I'm particularly having difficulty browsing images. I can't figure out the folder structure of images which Picasa seems to have created; I don't know where to find images, or how to control where things go, or why they're where they are, or how it relates to what's on my hard drive. I could probably read a tutorial, but plenty of other programs are intuitive. Is there some reason why Picasa creates a new folder structure which seems to bear a very complex - apparently random - relationship to the folder structure of the source images?

• Answer:

  A reason to drop Picasa. There are so much more products that work as they should.