Apple does not directly manufacture 100%. They get parts from Samsung, Toshiba, Nvidia Intel among many others. The issue i have is while i kept watching the keynote everything about the new MBP's the guy finished with "it ships today" ....Apple does this every year.
Correct, Apple doesn't make most of the components that go into the products but all the final products are Apple-branded with an Apple-controlled supply chain and sold in Apple stores.
IMO I think Google should be able to do the same. When JellyBean is released. I promise you that Google is already building and possibly testing internal Alpha candidates for the next OS. Now i know Google can't control other manufacturers like HTC and Samsung..but take the Nexus line for instance. They should be able to announce firm dates. Before you say anything about the carriers interfering ......that doesn't stop Apple with the Iphone. However i realize Apple's pockets are deeper.
The last 1/2 of this is what the other poster was talking about. GOOGLE isn't building the devices that the OS is going onto, they rely on other manufacturers such as HTC, Motorola, Samsung to build the devices and then that manufacturer has to ensure there's an OS build that is stable for their device. You think HTC, Motorola and Samsung build ALL the components that go into their phones? Heck, half the components in the phones are probably identical.
The Nexus phones get the new OS almost instantly when Google releases it, they are a "Google Experience Device", it's as pure as Android will get on a device. Apple releases iOS updates without carrier delay because they dictated to the carriers that the carrier would have zero influence on the OS with none of the crapware that Android devices are getting forced on them, and if the carrier didn't agree they didn't get the iPhone (why do you think Verizon didn't get it the first couple years, they wanted more control than Apple would give them).
The difference between Android and iOS is that Android is open source. Once Google releases the final code for Android, then it falls on the developers for the handset manufacturers to customize it, but they can't do that until the final code is released. Regarding the wait for the updates, the handset makers have to make sure the new version will work on their devices so THEY then need to test builds once they have them ready for testing. The development cycle for Android is lengthened because it has to pass 2 QC departments, plus having to pass muster with the carriers (did the handset maker include all the bloatware we wanted?). Apple is testing the code on the very devices it will be deployed to and doesn't have to pass the carrier's testing, allowing the update to be available to all supported devices immediately.