They aren't but that's really semantics. It's labor being used by these western corporations. You are explicitly responsible for the labor you directly source but you are also implicitly responsible for the labor you source through the services/products you purchase.
Outsourcing labor intensive work to lower income regions is almost universally a good thing but that doesn't mean that western corporations shouldn't be held liable for that outsourced labor. What needs to change is that corporations need to be required to perform due diligence that the work they contract out is meeting at least some established international labor standard (likely a lower standard than the country the western corp is operating out of has).
In the case of ship breaking, what needs to change is that any western corporation that owns and/or operates a ship during the last few years of its life needs to be held directly responsible for that ship until after it has been scrapped. They can contract the work out and all that but they should not be able to sell the ship off to a scrapper in the last few months of its life and wash their hands of their responsibility.
How long that last few years should be probably needs to be class dependent and you should probably be able to push off that "last few years" time window with a re-certification process (i.e. showing the ship still has at least x years of life on it).
If western countries actually held their corporations liable and stopped them from blindly pawning off work, they could drag up labor standards in other countries without depriving those countries of the outsourced work that their economies are heavily supplemented by.