Indeed we cannot.

I remember what an older aussie guy I knew said, who had a chinese wife. He said something along the lines of, you could live here (China) for 10 years and still be an outsider and never even scratch the surface of the real culture. The fact is as foreigners we can never really know the true dynamics, and are kept in the dark intentionally and for other reasons, despite a good knowledge of mandarin and living in China a long time and so on.

The differences between mainland China and HK have been gotten into many times, and yes, I feel there are some real differences, although some are being eroded.