If the contract is voluntary it is advantageous to both or else it wouldn't be entered into.
Take this trade off. I create a system whereby I can make $100 for every hour someone works. I tell you I'll pay you $10 an hour to work. If you are better off working those hours you will take it and I will receive $90 and you $10. If you won't I'm out a lot of money, so I will probably revise my offer upwards.
These workers are individuals capable of making decisions. If they decide working for Amazon for $13 an hour is better than alternatives they should take it - if not they should pursue a more valuable alternative.
Take this trade off. I create a system whereby I can make $100 for every hour someone works. I tell you I'll pay you $10 an hour to work. If you are better off working those hours you will take it and I will receive $90 and you $10. If you won't I'm out a lot of money, so I will probably revise my offer upwards.
These workers are individuals capable of making decisions. If they decide working for Amazon for $13 an hour is better than alternatives they should take it - if not they should pursue a more valuable alternative.