In the introduction of the new Kindle products, Jeff Bezos said that it wants to make money when you use the device, not when you buy the device. But Amazon doesn’t make money during the overwhelming amount of time you use a Kindle. That would be closer to the model of a cellular carrier. No, Amazon makes money when you buy content (or rent or watch them as part of your Amazon Prime subscription). And while the comment was a bit of a jab at Apple, Apple also makes money when you buy content.
So, Amazon may have a stronger relative incentive to drive usability, but that incentive is offset a lot by the need to monetize after you’ve purchased the device. Once you’ve bought an iPad, Apple’s design of the user experience is also intended to drive satisfaction. Anything that it makes off the app store is still, at least at this point, gravy.