Maybe it's because nobody knows what the heck you're talking about?
How do you get the attachments (uploaded images) for all posts in a category?
Posts don't have attachments linked to them. The uploaded images/files that you upload using the upload manager are independent. They are not connected to a post in any particular fashion.
Well, that's not entirely true. They're connected to their own posts (attachments *are* posts, internally).. But they're just img tags or anchor tags in the post content themselves, for display purposes. There's no structure to connect a post you write to the attachments you choose to put into it.