Note there is no mention of, or charges relating to, trafficking, coercion or any kind of enforcement.
Can it be these numerous ladies referred to worked voluntarily?
Problem is the language barrier, and the girls usual failure to co-operate with the authorities makes getting a trafficking conviction difficult.
Also there's the problem that any coercion may be through pressure on the girls family, or through accrued debts which will still be payable back home, whatever happens in a UK court. Whatever happens here, the girl is still under a percieved risk.
I don't know anything about this case, but the fact its gone to court is interesting: there must be something significant going on for it to go to trial. There seems to have been more of a recent trend to just deport the brothel pimps and let the Chinese authorities pick up the pieces.