Intel Macs have never had typical BIOSes or standards compliant UEFI, to say nothing of their device drivers. Without Apple providing a HAL FLL for the windows

Intel Macs have never had typical BIOSes or standards compliant UEFI, to say nothing of their device drivers. Without Apple providing a HAL FLL for the windows executive and device drivers along with a special bootloader shim (the marketing guys call this package "Bootcamp"), Windows would not work on Intel Macs. Microsoft or some third party would have to reverse engineer the device drivers, and they're definitely not making that investment. Not to mention more basically that Apple has to sign the NT kernel for it to load on Macs without disabling the equivalent of SecureBoot.