One of Elon Musk’s worries was on full display at CES in Las Vegas this week. Chinese-made human-like robots were everywhere across the exhibition floor, playing table tennis, sweeping floors and practicing kung fu.China’s latest robotics innovations were delivered to the heart of America’s technology showcase, serving a constant reminder of the technological race between the world’s two biggest economies. While Santa Clara, California-based Nvidia Corp. and Advanced Micro Devices Inc. hosted ke...