The company is still using a person’s material situation to pay them less. More purchasing power in their subjective economy is part of their material situation. They are still receiving monetarily less as is their country.
I directly covered your second point, while they do spend the money they earn from their American job within their economy they are not being paid the exact value of their labor because profit is being extracted so the amount of money they stimulate their economy with is not as valuable as their labor would be. I don’t want to explain the entire labor theory of value here because it would take up too much time and space but you can look into it if you’d like. Put simply, the profit that company makes is extracted from that employees labor meaning that some of their labor is being used not to benefit their country or people but another’s. Outsourcing is an extraction of mans most valuable resource from the less fortunate to the more