This isn't quite fair. Google makes it virtually impossible for Amazon to add support to cast from its own devices (Kindle Fire, etc.). This is likely part of why Amazon added a Prime Video app for Android but refuses to allow casting support for other Android devices when its own devices cannot use it.
I don't, however, agree with Amazon's decision to not sell devices without Prime Video support. I don't think the case they make that customers will expect Prime Video support holds much merit. In any case, the Apple TV is expected to return now that the Prime Video app has been released on that platform.
I would like to see Chromecast support added to Prime Video, which is easiest if both sides concede slightly.
I don't, however, agree with Amazon's decision to not sell devices without Prime Video support. I don't think the case they make that customers will expect Prime Video support holds much merit. In any case, the Apple TV is expected to return now that the Prime Video app has been released on that platform.
I would like to see Chromecast support added to Prime Video, which is easiest if both sides concede slightly.