You can adapt humans as well. Bolt in the drill and a battery pack to the human "frame" and you're good to go. We're not Borg already only because "we have civil rights and we tend to riot if we are treated badly".
But much more expensive to adapt to a biological unit. The robot's drill can share the robot's power unit. Mine has to be plugged in; has to have its own motor; has to be shielded and safe.