I hate defending microsoft, however the problem is most users won't install an update. even today the average user is to stupid to understand how and why they should update.
Look at ios and Mac OS . iOS achieves something like an 75% updates installed within 3 months of it being released.
andriod or windows xp/7 which gets 25% of updates installed in 6 months.
The problem with comparing Apple with any other computer company is that Apple fully controls their product line. When Apple pushes an update they know exactly what the base hardware is (since they make it themselves). When Android and Microsoft push updates they have to worry that the update may adversely affect machines made by numerous hardware manufacturers. In Android's case the manufacturer of the device may not even make an updated OS for their older devices and loading Google's base Android OS isn't something many end users can/will do.