Apple uses a proprietary extensions for perfectly standart, even a bit outdated base EFI. Big difference with proprietary efi. Just for you to know - you can grab (opensorced, standart) UEFI, compile it yourself in MS Visual Studio under windows and Apple's extensions will perfectly load into it at runtime.
I'd recommend you read this:
http://msdn.microsoft.com/en-us/windows/hardware/gg463525
exactly pay attention to this:
* The GUID Partition Table (GPT) was introduced as part of the Unified Extensible Firmware Interface (UEFI) initiative.
and than - this:
Windows XP x64 Edition can use GPT disks for data only.
The 32-bit version will see only the Protective MBR. The EE partition will not be mounted or otherwise exposed to application software.
Starting with Windows Server 2003 Service Pack 1, all versions of Windows Server can use GPT partitioned disks for data. Booting is only supported for 64-bit editions on Itanium-based systems.
Can Windows 7, Windows Vista, and Windows Server 2008 read, write, and boot from GPT disks?
Yes, all versions can use GPT partitioned disks for data. Booting is only supported for 64-bit editions on UEFI-based systems.
Last one sounds good, yes? Actually no:
Windows GPT Required Partitions
EFI System Partition
What is the Extensible Firmware Interface System Partition (ESP)?
The ESP contains the NTLDR, HAL, Boot.txt, and other files… blabla
Do you really think that NTLDR, HAL, Boot.txt are parts of OS-independent UEFI standart?
…
Can there be two ESPs on a single disk?
Such a configuration should not be created and is not supported in Windows.
So Apple just can not create special win-specific partition for Windows to load directly - it just does not support it
Microsoft Reserved Partition
What disks require an MSR?
Every GPT disk must contain an MSR. The order of partitions on the disk should be ESP (if any), OEM (if any) and MSR followed by primary data partition(s). It is particularly important that the MSR be created before other primary data partitions.
Do you really think that Microsoft Reserved Partition is a part of OS-independent GUID GPT standart?
Q. Who creates the MSR?
The MSR must be created when disk-partitioning information is first written to the drive. If the manufacturer partitions the disk, the manufacturer must create the MSR at the same time.
So for windows to boot directly, Apple should themselves create windows non-standard partition on every mac sold.
And, furthermore, it (Apple) have to install NTLDR, HAL, Boot.txt and other MS crap on every mac. Paying license fee for that.
It's not my fantasies - it's open data from Windows Hardware Developer Center > Learn > Devices > Storage Technologies > Windows and GPT FAQ of MS itself.
And same story you can find about UEFI support on Windows. Non-standard things required here and there.
Do you know that Linux can boot on macs directly, as it doesn't require some MSR sh*t and such?
There are a lot of things to blame Apple, but not this one
