If you order a fire stick or a Kindle directly through Amazon, the device is already set up with your account info. If you purchase from a retail store, you have to register it yourself.
I’m sure there aren’t cubicles full of people plugging devices into a USB port and manually entering your info, but even if they have a way that only takes a few seconds, the device would still need to be repackaged. Lets say they have the process down to 20 seconds. Multiply that times thousands of devices, though.
As concerned as Amazon is with streamlining and efficiency, i’m surprised they aren’t just shipped as is, leaving it to the customer to register it. So what’s the process?