There is much to be said for both the weakness and strength of China's border controls. Surprising weakness can be found at the handful of points where the mainland physically connects with its two most subversive territories, aka the special administrative regions of Hong Kong and Macau. Strength is most often found, again perhaps surprisingly, at the millions of points where the mainland figuratively connects with the wider world, in cyberspace. Neither is as accidental as it may appear.
Hong Kong's border crossings with Guangdong are by far the busiest on the mainland - if not the world. In an average month, more than 8 million people pass through checkpoints to Hong Kong. The vast majority of this happens at Lowu (served by the Kowloon-Canton Railway Corporation) and Lok Ma Chau (for passenger and cargo vehicles).
There are also roughly 8,000 people who take the KCRC through-train from Hunghom to Guangzhou every day, and about 6,000 who catch the ferry from either the SkyPier at the airport, the China Ferry Terminal in Tsim Sha Tsui, or the Macau Ferry Terminal in Central, to Shenzhen and various port cities.
Then there is Shataukok. It probably has a few hundred border crossings a minute. But that's not because there is a flood of people passing through. It's because the people who live in this town on the eastern side of Shenzhen are crossing the street to do their shopping.
The boundary here is a white line. I haven't visited the place yet, because I haven't been able to get a police permit. But I look forward to the day when I can go in from the mainland side on a tour organised by a travel agency. Until then, I am going to have to remain assured that it deserves its reputation as a smuggling den.
But, to be frank, every border crossing is a smuggler's den. Any reader of this ought to remember a time when they took a book or magazine into the mainland with them. Was it licensed for distribution?
Anyway, the point is this. When Hong Kong's media start thundering about the need for 'extreme vigilance' at 'our borders' to protect 'our people' from bird flu outbreaks on the mainland, they might want to send some reporters to these boundary crossings to see what the reality is like on the ground.