While Apple battles the FBI over their demand for software to unlock an iPhone, Amazon has disabled encryption in its Fire devices. Any device running FireOS 5 or later will no longer support encryption.
FireOS is used on Fire phones and the Kindle Fire tablet, and is Amazon's derivative of the Android mobile operating system. Phones and tablets can contain a great deal of personal information, and encrypting them secures this data if they are lost or stolen.
According to Amazon, few customers were using encryption (it was an optional feature), and communication between FireOS devices and Amazon's cloud servers is still encrypted. Encrypted communication doesn't help if a device is stolen, though, when the data can obtained directly from the device.
Why do this? The Kindle Fire doesn't have a great deal of processing power, and the encryption overhead would slow it down significantly. But given that encryption was optional, it seems to be a weird decision that is out of step with its competitors. The iPad supports encryption, and Google seems to be mandating encryption for Android 6.