Any iOS application developer who wants his titles to be searchable in the App Store must be very well "equipped" to test his creations in any conditions. In the image above you have one "work bench" of a normal developer who tests his applications on no less than 12 iDevices with 8 different versions of iOS before releasing them in the App Store. Such a great diversity in the iDevices used for tests guarantees users that the application will work well no matter what version of iOS they have in their own terminal.
I can test anything from iOS 3.1 through iOS 5. The older OS versions are especially helpful to keep around since it is essentially impossible to replicate an issue on iOS 3.X without having a dedicated device kicking around. While taking this picture I was struck by how little the form factor of the iOS lineup has changed in the last 5 years. From above they all look almost identical.
Unfortunately, not everyone who develops applications for iOS can afford to buy so many iDevices, so when an application closes by itself or generates errors, you have to think that it was probably tested on not too many versions of iOS and probably on non-jailbroken iDevices.
