In China, queueing is honored more in the breach than in the observance. If you see a line for something, you must understand that what you are seeing is not really a line. It is a one-dimensional mob. You must be prepared to defend your position in line fiercely, because any sign of weakness will be pounced upon, and the next thing you know, five people just cut in front of you.
I first became aware of this characteristic of "Chinese queueing theory" while still at the airport. When the gate agents announced that the flight to Beijing had begun boarding, a one-dimensional mob quickly formed, and I naïvely joined the end. It wasn't long before my lack of attentiveness to the minuscule open space in front of me resulted in another person cutting in front. At that point, I realized that the Chinese implementation of queueing theory was already in effect even before we left the United States.
As another example: After the plane pulls up to the gate after landing, the aisles quickly fill with people anxious to get off the plane. In the United States, you can rely upon the kindness of strangers to let you into the aisle so you can fetch your bags and join the queue. But in China, you must force your way into the aisle. Nobody is going to let you in.
Colleagues of mine who have spent time in both China and the United States tell me that it's an adjustment they have to make whenever they travel between the two countries. For example, in the United States, it is understood that when you are waiting in line for the ATM, you allow the person at the ATM a few feet of "privacy space." On the other hand, in China, you cannot leave such an allowance, because that is a sign of weakness in the one-dimensional mob. You have to stand right behind the person to protect your place in line.
Bonus airport observation: How ironic it is that your last meal in your home country often comes from a crappy airport crfeteria.