I think that the rise of Amazon as the primary retailer leaves the delivery market ripe for upheaval. The current delivery model is kind of awkward: they do a first delivery when you're at work, and then trying to coordinate with them becomes a huge hassle. I usually end up having packages delivered to my parents' house, since they won't leave packages at my door at my current apartment (and rightfully so!)
To me, it seems like it's in Amazon's best interest to use a delivery service that is more convenient for the end user than the current model, like picking from available delivery dates and times.