Most of abandoned devices out there are by third party Android cellphone makers, who have a lot of incentive of making users just buy the new version. After all, it's their only revenue stream.
Apple, on the other hand, besides being traditionally nicer to its customers (as shown by them toping the user and support satisfaction surveys every damn year), also have the iTunes and iPhone App Store to get money off of customers with older iPhones, so they can afford to give them a new iOS version. And they also use the iPhone as a lure to their other device offerings (iPad, Macs, etc), so the benefit from users of an older iPhone not feeling left behind iOS-wise.
Perhaps the biggest reason is this: Apple still sells older models (such as the 3GS, 4G etc), especially to other parts of the world. So it's an added incentive that those are upgradable to the latest iOS.
Now, since you asked, perhaps Google doesn't want to add to their Android dev expenses the potentially huge expense of supporting older devices.
Most of abandoned devices out there are by third party Android cellphone makers, who have a lot of incentive of making users just buy the new version. After all, it's their only revenue stream.
Apple, on the other hand, besides being traditionally nicer to its customers (as shown by them toping the user and support satisfaction surveys every damn year), also have the iTunes and iPhone App Store to get money off of customers with older iPhones, so they can afford to give them a new iOS version. And they also use the iPhone as a lure to their other device offerings (iPad, Macs, etc), so the benefit from users of an older iPhone not feeling left behind iOS-wise.
Perhaps the biggest reason is this: Apple still sells older models (such as the 3GS, 4G etc), especially to other parts of the world. So it's an added incentive that those are upgradable to the latest iOS.
Now, since you asked, perhaps Google doesn't want to add to their Android dev expenses the potentially huge expense of supporting older devices.