I've assumed that's been coming for a while—Amazon ships you something they think you'll want, and you ship it back if you don't. There are probably legal hurdles, but.
Starting with the fact that, in the U. S. at least, if you didn't order it, you get to keep it. IANAL, but that could probably be signed away in the agreement or something.
I think there are ways around it. I get a book every year from Cooks Illustrated, and I don't ask for it, but about a month before they send it, they send me a letter telling me "we're going to send you this book unless you respond back to this letter". Which is really scummy, but I do want the book, so I let them.
I hope you didn't pay them for it. Telling me up front you're going to send something, while expecting payment, unless action is taken on my part does not absolve them of letting you keep the item free of charge.
Put another way, shit shows up in my mailbox for which I took zero action? Mine now.