walk away from the main streets of beijing, you might come across small blocks resided by migrant workers and other low class people. if you are carried to here with eyes wrapped, you won't believe it is part of beijing, the capital city of china. in short, these districts are slums.
the upward mobility for labor class in china is seriously limited due to the fact that higher education is only available to a small part of the gifted students from rural areas and, the living costs are particularly high in big cities for migrant workers.
"slums" in beijing, not matter how embarrassing they are to beijingers, provide a low-cost way of life for migrant workers to merge themselves into the new city life, and the door of opportunities opens for them and their children.
a migrant worker takes a nap on the top of his "shop" in a beijing street, the famous SIT cafe is located nearby and, chinese and foreign students/white-collar pass by him to SIT cafe to read, date, surf the web and drink espresso
unlike beijing, shanghai resists the invasions of "slums" and becomes a place full of polite hostilities to migrant workers. unless a migrant worker could find a job in a firm that provides dormitory, it is very very hard for him to find a affordable place to live.
before the government has the fund to assist migrant workers to fit into the city, perhaps it's not a bad idea for shanghai to have a few slums, certainly management is a must in order to prevent crime and maintain the sanitation levels.