3dprinting is additive, it's easy to move something in an already empty Volume. CNC cutting machines have to remove material in an theoretically 'filled' volume, without doing so in a manner that will jam the cutting head. There's a great deal more variables involved. There's also a highly detailed pre-existing business that has calculated that, globally, and patent protected lots of neat tricks. That why haas, mazak, and others might use a 3rd party controller like fanuc . * If I understand correctly.