Kindle is a particularly bad example. Kindle forked Android, so are not under control of Google. In principle, other manufacturers could also do this, but in practice it's practically impossible because they'd loose Google Play.

http://arstechnica.com/gadgets/2013/10/googles-iron-grip-on-...

Thanks for the correction - updated my answer.

But when you're honest: How many users are willing to use the device without connection to the Google ecosystem? It's the same on iOS. My point of criticism remains the same: The data you're (then) generating in the Google ecosystem has a higher value than in any other ecosystem (Apple, Microsoft, etc.) and more likely makes you a product (and not free).