It's why we don't have fruit-flavored milk, Crystal Pepsi, or square eggs. Businesses react or they die. Manufacturers have the power to negotiate their contracts with suppliers and vendors. They have the power to insist on fair wages and healthy working conditions. By staying in poor countries and offering better jobs, they can address the poverty that drives exploitation of workers.
Businesses have the power to act in the interest of economic and social justice.
Some do it now. But some will do it only if it's the best way to make money. One bit of economic pressure at a time changed a nation. I believe sweatshops and child labor will be the next issue to engage the conscience of Americans. Businesses, led by the national group, Business for Social Responsibility, have already started meeting on setting standards.