Sounds a bit more complicated than the usual street food operation...
Then again, I do notice around here that a certain amount of copying goes on. If one guy is successful, say, with shandong jianbing, it used to be that he'd for the most part be respected and people would leave his operation alone, but in recent years other guys have floated in and set up similar carts. Presumably there's some behind the scene rivalry, but it isn't apparent on the street.
Plus, is Zheng doing the stretchy noodle thing, where you make dough then stretch it and slap it around until it becomes strands? Don't the, um, north western province minorities have a lock on that kind of thing?
Also, how do street vendors have employees? That's what family members are for, isn't it? How is she trusted to hold money during the night and not run away? Or for that matter, how is she trusted to not pocket half of the evening's take?
ETA: I'm remembering a blogger, female, Chinese (or maybe Chinese American), a few years ago, who went and lived with migrant worker, street food seller types, and then blogged the story. It was pretty gross. Especially about food prep and living conditions.
Can't remember a name or a link...