"First come, first served" is very common and widely accepted in Western countries, but not always in mainland China.
For service marketers, first come first served may be a good policy to avoid the service failure from the perspective of customers who stand or wait in line to get their service. It relates to a critical issue of "procedural justice" when customer do attribute their treatment by the service provider, in marketing practice and theory.
Standing in a line in a retail setting in Taiwan is quite new, just 20 years back since McDonald's entered the market. That has been an education for Chinese consumers in Taiwan.
Silent word of mouth is a Me-too psychology where Chinese consumers do not like to fall far behind their peers. The results are powerful for retailers who are able to take advantage of it. Doing so, however, is not easy, as Clyde says, "You need a line to get a line in a Chinese setting."
Fads tend to influence long lines at retailers, from egg tarts (Dan Ta) to doughnuts. Any product is possible to catch on and lead to long lines, but food seems to be most common.
When people stand in long cues to purchase a product, it is a silent word of mouth.