Because xemu does not yet have these complex DRM functions fully implemented, in the emulator. You must use a modified or "hacked" retail BIOS.
The original Microsoft Xbox relies on a Basic Input/Output System (BIOS) stored in its flash memory. This firmware initializes the custom Intel Pentium III CPU and Nvidia NV2A GPU. It also enforces strict Digital Rights Management (DRM) to ensure only authorized, retail game discs can boot. Xemu Complex 4627 Bios
It handles memory management and core Xbox kernels with the exact stability xemu expects. Because xemu does not yet have these complex
If completed correctly, you will be greeted by the classic green flubber animation and the original Xbox dashboard. OGXbox Archivehttps://www.ogxbox.co.uk Xbox Bios Complex 4627 - OGXbox Archive Xemu Complex 4627 Bios
It boots both NTSC and PAL game titles seamlessly.