Gary's random little things about China:

Where's my soy sauce?

When you sit down to eat at a restaurant in China, you will almost never see a bottle of soy sauce on the table like you might at a Chinese restaurant in the USA or UK.
In Chinese cooking culture, soy sauce is a seasoning reserved for use in the kitchen.
The fact that soy sauce can be found at Chinese restaurants outside of China probably comes from westerner confusion between Japanese food and Chinese food.
The most popular Japanese food outside of Japan is sushi, which of course is always served with soy sauce. This is the most likely reason that soy sauce migrated out of the kitchen on onto the table at your Chinese restaurant in the west.