Here's a way for you to solve the problem. Offer those workers better pay and conditions than what Facebook is offering. So far nobody's stepped up to the plate.
Because this is so stupid as saying to someone to solve the problem of slavery starting to pay the workers. The problem is that in a market where there's cheaper products being produced because someone doesn't pay for the labor force, someone who give salaries will be in economic disadvantage. The logic is the same if you substitute "slavery" with "bad conditions and poor salaries". When a problem is in the system, you can't solve it just changing individual attitudes.
You can by all means tell us how to solve it. Right now Facebook's the best job offer they got, you can't just wish that fact away. I guess you could do what the GP wanted and create a competing product that drives them out of the job?
> The logic is the same if you substitute "slavery" with "bad conditions and poor salaries".
No, it's not the same. Slavery is an entirely different kind of bargaining position.