Apple can get away with less RAM because the flash storage is blazing fast and attached directly to the CPU, making swap much more painless than on most Windows machines that get bottom-of-the-barrel storage and controllers.

Yes, that's exactly what I'm talking about: Apple can do that because everyone involved works at the same place and owns the success or failure of the product. Google or Microsoft have to be a lot more conservative because they have limited ability to force the hardware vendors to do something and they'll probably get blamed more if it doesn't work well: people are primed to say “Windows <version + 1> sucks!” even if the real answer is that their PC was marginally-specced when they bought it 5 years ago.