Well paid workers are not slaves. They not be well paid by our standards, but they are by their standards. That is why manufactoring labour moves there.
The only thing capitalists do is brutally exploit people and the environment. The only reason they're in other countries is to brutally exploit them and their environment more.
Exploitation is more often then not a mutual thing. It is absurd to call it brutal. In this case it increased their standard of living, and working considtions.