So it's OK to exploit immigrant workers in the USA because they could walk out if they wanted to, but not OK to exploit Chinese peasants and families who move to factory towns in pursuit of work. But by your logic, they too could walk out. Why the difference? A cynic might observe that concern about exploitation seems carefully to be targeted on things you do not want, with your own exploitation rationalized away. Perhaps people who want iPhones discriminate in the same fashion which is why nothing ever changes. Seems to me that exploitation is exploitation, and exploitation of workers to shave a few pennies off the cost of the lettuce leaves you will eat this week, is happening every day.