Elon Musk claimed this week that Tesla’s humanoid robots will be “the biggest ... he’ll manage to put a robot in every house.

"Why?" I asked. "I am not sure I understand why yet." Not an altogether terrible answer from Sophia, an AI robot, in an interview with Business Insider last week at Web Summit in Lisbon.

The “talking” robot, nicknamed Ushi-kun, has helped drive up sales by 10-20 percent since it went into operation in late July at the Awaji Service Area on the inbound lane of the Kobe-Awaji ...