Evaluations of teachers may be helpful as well as obstructive and destructive for all parties involved. It depends on how they are used and/or what they consist of. This practise is fairly new to mainland and locals often do not know what or how to ask and then what to do with the results. Then, I doubt Chinese unis use the same evaluation process for their local teaching staff as for their foreing one, but forgive me if I am wrong. Further more, teachers evaluations when students get their chances to answer some questions on their teachers, usually get that feeling that they've got some "powers". So, knowing this, both, the teachers and students approach their jobs in less academic way. My observation is that many evaluations of foreign teachers on mainland are poorly done and quite inefficient as the local employers and their management staff aren't up to the task. I don't believe other unis around ask for such documents, although there's a regulation for letters of Recommendation. Evaluations, if they are positive, could protect a ft in a long run then.
Cheers and beers