"Amazon does not care about app sales"

Amazon would have to be blind to their own success selling one type of virtual good to kindle owners for them to not care about selling another type of virtual good to kindle owners.

As others have pointed out, the fact that they went through the trouble of building their own App Store proves they care deeply about app sales.

What's more, the low margins on the kindle fire prove they not only care about app sales (and book sales, and movie sales, and music sales), they're relying on them.