First, Amazon is in the tablet business, which is a very different beast from phones. Case in point: carriers.
Also, they're selling Fire tablets at below cost. That'd be horrifying for Nokia's finances. Not to mention that Kindle Fire's sales crashed hard after the initial holiday rush.
http://www.readwriteweb.com/mobile/2012/05/amazons-kindle-fi...
Meanwhile, LG, Sony, Acer, etc. etc. are in losses with Android and HTC is barely ekeing out a small profit. That demonstrates, how smart Nokia was not to just into this pool