Even if Tesla builds the robots elsewhere, it will still depend heavily on China. Whether the servomotors that drive a humanoid's joints, the harmonic reducers that give it fluid movement, the force and torque sensors, the machine-vision modules, the LFP batteries that stabilize its center of gravity, and the aluminum alloys and specialty steels that form its skeleton — China leads in production, cost, and refinement for nearly all of them. Musk can diversify assembly, but he cannot escape de...