Actually, Amazon does not use the Google Play services and app suite, so they can do anything they like, and they do, with the Android SDK which is also mostly Apache licensed.
In a sense they are freeloading. But Google long ago took the gamble that having a broad community, that might include competitors, using the Android OS and creating apps for the Android runtime environment is better than trying to do it all in-house and proprietary.
In a sense they are freeloading. But Google long ago took the gamble that having a broad community, that might include competitors, using the Android OS and creating apps for the Android runtime environment is better than trying to do it all in-house and proprietary.