If an American company opens a plant overseas, is it exploiting its workers? Some people would say, yes, unless the workers have the same pay, benefits, and working conditions as American workers. But companies do not build factories in other countries unless it is to their advantage, and that means it must be cheaper. One of the easiest ways for it to be cheaper is for workers to be paid less. By this definition, the answer is always yes, it is exploiting the workers.
If an American company builds a plant in another state where wages are less, is it exploiting its workers? Americans move freely between states and presumably could get jobs elsewhere, so we usually say no to that question. For decades people moved into Michigan because of the automobile industry. Detroit’s dramatic population decline is a testimony to the fact that they did not stay when the jobs left.
Overseas workers often do not have the choice of moving to a place where there are better jobs, but they do have a choice of whether to work in a factory owned by Americans. They are not slaves and can quit. They don’t quit because there are no better jobs. Many Americans work at jobs that are underpaid, unpleasant, or dangerous because it pays better than “Do you want fries with that?”
Unions limit the exploitation, based on the power of the group. A company might be able to replace a few workers who quit over low pay or bad working conditions, but it could not replace all of them. Many people who are pro union would cross a picket line to feed their families.
Oddly enough, the absence of unions in overseas plants suggests they are not exploiting workers.