Before autonomous driving took root in Beijing, thousands of workers in China's Guizhou province taught artificial intelligence by data labeling. This work, done far from major cities, involved marking buildings and roads to shape AI capabilities.

Before autonomous driving freed up the hands of Beijing’s middle class, thousands of workers some 1,500km (930 miles) away in China’s southwestern Guizhou province clicked away at computer screens to teach AI about navigating traffic. In the mountainous city of Tongren, where incomes are less than half those in Beijing, the work of data labelling – marking residential buildings, pavements, roadways and traffic lights – shaped the artificial intelligence guiding those vehicles. The job required.....