If you're talking video playback, those computers were usually bundled with a piece of software that paid the fees. I've seen PowerDVD HD bundled with a few OEM computers. (Granted I don't see a lot of OEM computers) If Apple were to adopt BD proper, they would integrate it heavily into the OS.
Why would Apple do such a thing ? If Microsoft can find a way to provide APIs that are good enough for 3rd parties to implement the functionality in userspace, why would Apple go out of their way to stuff it into kernelspace ? That makes no sense. You want to move stuff out of kernelspace, which should be reserved to hardware abstraction and OS level services as much as possible. Blu-ray playback is not an OS level service, it's very much an application.
The truth of the matter is Microsoft implemented AACS, Apple refuses to do so (they already both support HDCP). This is the "bag of hurt" so to speak as matticus pointed out. Except the licensing issues are not complicated. There remains only to go ahead and implement.
It's not a particularly invasive technology to begin with. This is plain Apple being lazy.