Why do I have problems sending samples by air to Shenzhen, but not if sent through Hong Kong?

Full Question

I often need to send samples and key components to my supplier in Shenzhen. I find that I have lots of problems when I send via air direct to Shenzhen, but not so many problems if I send via air to Hong Kong then overland into Shenzhen. Can you help explain this?

Answer

I bet it is one of the following two reasons-

1. Local customs officers in China (especially Mainland) have a lot of room to interpret the rules and regulations as they see fit. So if your shipment gets stuck, it is up to you to explain to the officer's satisfaction the details of the shipment. It is not common that you have the ability to go to a supervisor or supervisor's supervisor to sort things out. Often the problem solving comes down to person to person relations. I am not saying relationships based on bribes, to the contrary, I am just referring to normal professional relationships where the parties involved have some prior knowledge of the other. Maybe the shipping company that you are using is well versed in Hong Kong (HK) and/or the overland borders into ShenZhen (SZ), but not so effective at the SZ airport because of lack of contacts or experience dealing with the system at the airport.
2. Items shipped air direct to SZ Airport have a much higher rate of problems because
   1. The customs officials there are very strict compared to sea and land ports
   2. The volume is low compared to truck via HK, so they check a higher percentage of items
   3. If problems are found, it is harder for your agent to fix things at the airport rather than SZ land/sea port because, unlike a truck, they can't easily turn a plane around and send it back to HK to try again.