I noticed that it is pretty much common sense and done on a needs basis.
When I'm with travelling luggages or bulky shopping items, the taxi driver usually come out to help, at least to help ensure that it fit into the trunk properly and the trunk is then securely closed. And I mean in Singapore. Of there're times when the driver just click the trunk open and I'd have to manage the rest myself. There're also times that I'd wave the driver who's halfway out of his seat that it's OK, thanks, but I could manage.
Yes, it's all play by ears and commonsense. And it's also commonsense that Quan Yifeng has an able-bodied male companion, isn't it? Why should the driver bother when her companion is idling ungentlemanly? Another possibility is that the driver recognises Quan and doesn't like her to begin with; just wants to get the journey over and done with, nothing more, nothing less, whereas Quan was expecting value-added celebrity service.