I think a TA is not needed, even for teachers who don't know Chinese. Obviously a Chinese speaking FT does not need anyone for translation and interpretation.

You being interested only in teaching college students, a TA is not so necessary. But what about senior high schools?
However, for me, at senior high schools, a TA is extremely advantageous, and I am very willing to work for a lower salary so as to have one. I prefer to let my TA do the classroom management in its entirety, as well as assist me planning my lessons. Being very lazy, I can exert myself minimally in class with my TA dealing with issues of discipline and doing the necessary explanations in Chinese instead of me doing them in English to pupils with bad listening and very limited vocabulary. Learning Chinese to a high level to achieve the above is something I'm not prepared to undertake, it's very boring.
For noobs teaching at senior high schools, I think a TA is a great boon, especially in the Chinese outback high schools, whose pupils tend to have very poor listening skills. Yuncheng agents are the way to go in this respect. EV Training Center is wrongly named - it is principally an agent for public senior high schools. IELTS School is wrongly named too, and is also an agent supplying public senior high schools with FTs and TAs.
At Yuncheng's outback schools the FTs with their TAs are often asked by the Chinese staff to teach listening. The Chinese teachers know the pupils' oral English is too poor for them to make much improvement in just 45 minutes' contact time /week in classes of 40+ pupils.