I don't think they are authorized to rent DVDs. Why do you say they are? See the MPAA document: http://www.mpaa.org/Resources/2146a1b0-20bd-48ce-a473-f5f27812ba29.pdf It makes sense that they're not authorized - how else can they rent for $1.99? Never get that from Blockbuster. Blockbuster has a special deal with the studios as I understand it. They pay way more for the same movie disc that we can buy from Walmart for $15.

Your logic makes sense to me, up to the point where you mention the name Blockbuster. Blockbuster has a license to rent DVDs. Zendiva does not. Can't really compare then.