Xing Wei graduated from a vocational high school in northeastern China in 2003 and went to work as an electrician in an auto parts factory in the country’s south. The only set of wheels he could afford was a black, three-speed bicycle. He earned $1,150 a year and shared a sweltering dormitory room with three other workers. “There was air-conditioning, but because we had to pay the electricity ourselves, we basically didn’t turn it on,” Mr. Xing said. Two decades later, Mr. Xing, 42, makes close to $60,000 a year.…