I am sorry to disappoint you but nothing was lifted from Rails Recipes. I would like to find you a recipe that mixes join models and polymorphism in Rails Recipe. I wrote the last 2 recipes in that chapter and that code is taken straight out (in simplified form) from one of my applications. I actually wrote the join model and polymorphism one and then I was asked to write one just about polymorphism as introduction to the concepts. The editor thought that my recipe was a little too advanced.
Your point about using common objects names that people can relate to (Magazine, Readers, Subscriptions, Cart, PhoneNumber, Company, People, Blog, Post) is plain silly.
You are pretty much saying that since Chad used those models in his book nobody else can write examples about activerecord using those same names.
I am sorry to disappoint you again, but many of those same examples that you found on Chad's book were available on the net in form of blog post, comments or documentation.
It's like saying nobody can talk about the "stack" example without "lifting" from somebody else.
Originally that recipe had User Subscribing to other Users and their Bookmarks and Subscriptions. I thought that as an example in a book those objects weren't easy to relate to in that context. So I changed them to Reader, Newspaper and Magazine.