There is no postal coding in Hong Kong, which is a special administrative entity of China but does have its own airport. When Hong Kong was still a British colony, the British authorities who were in charge of the territory did not want to spend the money necessary to develop a post code system. As a result, the territory does not have a post code system.
After China regained control of Hong Kong in 1997, the Chinese government decided against spending the necessary funds to introduce a post code system throughout the territory. Because Hong Kong was once a British colony, the British government did not want to spend the money necessary to develop a post code system when Hong Kong was still under their control. As a result, Hong Kong does not have a post code system.
After China regained control of Hong Kong in 1997, the Chinese government decided against implementing a post code system because they did not wish to spend the necessary funds on doing so.