Imho, it's perfectly reasonable for Google to include Play Services as a requirement to OEMs running managed Android (as opposed to custom compiled flavors based on AOSP). Don't you agree?
Google's agreement for this is in fact, illegal anticompetitive tying (or bundling, if you prefer). Requiring that in order to support Chromecast, Amazon must include Google Play Books is a very questionable requirement legally, especially considering the other highly dominant apps they require, like Google Search, Google Maps, and Google Chrome. In almost every civilized country, it's illegal for a company to use one monopoly to expand it's reach into another market. (Like to use these bundling requirements to encroach on the Kindle ebook market.)
If, as you suggest, however, it's perfectly reasonable to require all this of Amazon in exchange for Kindle support, isn't it perfectly reasonable for Amazon to decide not to sell hardware not compatible with their products?
Can you please cite where you got this information from?
"Over the last three years, Prime Video has become an important part of Prime," the statement says. "It's important that the streaming media players we sell interact well with Prime Video in order to avoid customer confusion."
http://money.cnn.com/2015/10/01/technology/amazon-bans-apple...
Combined this with Google's relatively secret (but well known to you, oh avid reader of my comments here) Mobile Applications Distribution Agreement (or MADA) which places heavy requirements on what Android devices can be if they have Google Play Services, like forbidding so-called "incompatible forks".
I mean, bitmapbrother, it only makes sense that Amazon only sells products compatible with their own products. The Apple Store doesn't sell chargers for the Galaxy S8! That would be madness. If Google wants their products sold on Amazon, they should feel free to loosen up their license restrictions to permit compatibility.
Also, Amazon is free to use Google Services providing their devices pass the CTS. In fact, their rumored Ice phones will use GMS.
Google behaved anticompetitively, Amazon responded in turn, but unfortunately, very few people are aware of the former.
(And yes, Google's anticompetitive behavior regarding Android apps and services is subject to another, separate EU antitrust investigation than the one mentioned above, which is still ongoing.)