I wish I had mod points, because this is exactly the issue.
Let's say someone puts their Kindle up on eBay, and then after it sells calls Amazon and says that the device got stolen. How is Amazon supposed to know whether the device whether the device was stolen or not? Even worse, what happens if Amazon believes someone claiming to own your device and bricks it, where does that put them?
It's entirely reasonable that Amazon won't do anything without a direct request from the cops (or presumably a court order).