This service, on the other hand, seems completely reasonable. It's easy to implement with mostly existing infrastructure. The delivery trucks and drivers are already out there, GPS-enabled connected cars are already out there, all that's needed is something that lets the delivery driver talk to the car. This could be something as simple as a QR code on the package that opens a URL that shows the car's location and has a button for opening the trunk. It's a service that's actually useful: getting packages when you work all day is an ongoing problem for a lot of people.
A brief aside: "next day delivery" is hardly an innovation of Amazon. I remember catalogs in the late 80s or early 90s which prominently advertised "same day" service if you called in your order by, say, 3AM.
Keep in mind that it took >5 years for Prime and AWS to take off. When they first launched, they lacked many features and no one gave a second look at them.
Using car boots for delivery might not work with a single manufacturer, but it might work for all manufacturers. It might also work more effectively with driverless cars. Either way it's an experiment to push the boundaries of what can make their supply chain more efficient.
Believe it or not they do that at GoDaddy too.