The movement of American companies has the potential to harm people in at least two ways.
First, it can lead to environmental degradation. Governments in developing nations are often willing to look the other way on environmental regulations (if those exist) in order to attract those companies. The companies can then pollute the environment.
Second, it can be economically harmful to the people. Arguably, American (and other rich world countries’) companies can exploit the low-wage labor in developing countries without helping the countries develop. Their presence retards the development of a domestic economy because it takes all the resources away from domestic companies.