I think it's because Amazon is going to use their own delivery vans. Across from the giant fulfillment center in Kenosha is another warehouse with tons of brand new little sprinter vans all ready to go.
In essence, it seems that Amazon is beginning to prefer the reliability of a private fleet over Vlad the Crazy Cossack.
I can't imagine where they might have gotten the idea.
That's my guess, anyway.