I have a PPC mac and I want to know why crossover programs like Bootcamp don’t work on PPC macs.

Microsoft Windows is written specifically to run on CPUs that use the x86 instruction sets (i.e. Intel and AMD processors).

Motorola's PowerPC processors do not use the x86 instruction sets so it cannot run Windows natively. That is why you can't use Bootcamp on PPC Macs.

The only way you can run Microsoft Windows on a PPC Mac would be to use an emulation program such as VirtualPC, which translates the Windows' x86 language to the RISC language that the PowerPC CPU can understand. This added translation layer makes it very slow however.

Hope this helps.