> but for the end user, they don't receive a patch of say 15MB with what has changed.
Yes they do: http://cdn.macrumors.com/article-new/2013/09/ios_7_0_2.jpg (since iOS 5).
Yes they do: http://cdn.macrumors.com/article-new/2013/09/ios_7_0_2.jpg (since iOS 5).