Originally Posted by Phil21

Because Apple controls the whole hardware/software stack, and can thus plan accordingly.

It's the same reason console games (xbox, ps3, etc.) run "flawlessly" compared to PC games. The developers only need to code for one configuration, vs. literally hundreds of millions of different possible hardware configs.

Something like sleep sounds easy, but in practice has been implemented in so many different ways depending on the individual manufacturer it becomes quite complex. Since Apple knows what hardware they need to support beforehand, they can simply code to those specs vs. trying to support 300 random buggy implementations of the same thing.

There are lots of "advanced" features modern PC's support these days, that most OS's simply don't even try to take full advantage of yet.