Rival Netflix can be found on both devices, but Amazon's streaming service has been notably absent, and the Amazon stopped stocking both devices in October last year.
According to Amazon CEO Jeff Bezos speaking at Recode's Code Conference, the decision to keep Prime off these devices is to do with the absence of "acceptable business terms."
Bezos refused to respond to a follow up question about whether these "acceptable business terms" referred to the 30% cut that Apple takes from all purchases made through its devices.
At the time of the decision it was speculated that the decision was due to Apple and Google offering hardware that competed with Amazon's Fire TV set-top boxes and streaming sticks.
By keeping Amazon Prime Video off its competitors' devices, Amazon was thought to be working to push consumers towards its own devices.
The use of the phrase "acceptable business terms" however implies that the disagreement is bigger than just this competition.
Amazon Prime Video continues to be available on Roku boxes which are still sold through Amazon's store. Meanwhile searching for either Chromecast or Apple TV brings up Amazon's own Fire TV devices.
Via The Verge