beggars in Hong Kong

Whenever I walk through anywhere in Hong Kong, there are beggars everywhere. Some of them look homeless. Some of them has disability problem. They always draw my attention and my pity. However, why do they appear in the street?

Hong Kong Social welfare is considered as one of the best in the world for poor and disable. The government will spend more than three billions of dollars to support the "weak" citizens in this year. Why do beggars appearing in the street? Does it means the society abandon them? The answer is no. Most of the baggers in Hong Kong are not qualify to receive the welfare and most of them are considered as mainlanders from China. They come to Hong Kong and beg for their living. Then, they return to mainland at night. Some of them are even consider as begging corporations. They provide transports for the beggars entering and leaving Hong Kong by sharing the beggars "income". Which means a part of anyone's donations is given to these "transporters". Is it something that a donator wishes to provide a method for the “transporters” to make money from the unfortunates?