Starting in September, Wang Ming’s 12-year-old son will need to go to school in a city 120km (75 miles) from his home in Beijing.Originally from northeastern China, Wang and his wife have lived in Beijing for more than 20 years.But even though they work for a bank and insurance company they have never been able to obtain a hukou – the household registration document that serves as proof of residency and grants access to public services such as healthcare and education.The hukou system has...