Anodizing is a process involving several variables that have to be controlled, and is also affected by the grade and treatment of the aluminum.
There's no free lunch. A lot of people think the whole story behind Chinese lights being less expensive "for what you get"(in most cases I'd say for what you perceive you're getting) is cheap labor vs. expensive labor and brand recognition, but you're also dealing with uncontrolled manufacturing with unknown raw materials.
We don't know if the aluminum was tempered or anodized properly. We don't even know if it was the same grade of aluminum as the marketing claimed. We have no way of knowing, so we take it at face value, but over and over we see the inferior results.
I think it's no accident "type III hard anodized" finishes from Fenix, NiteCore, or 4Sevens(my experience, I'm sure there are plenty of others) consistently show wear many times as quickly as type II ano from Streamlight or Surefire, and are visibly different in new appearance from type III ano by SF, Arc, and some Chinese companies like Zebralight and Jetbeam, and even more visibly different after impacts or wear.
Google: "aluminum temper", "aluminum grade", "anodizing aluminum", and "you get what you pay for"