The only assumption is that people will make the decision that is in their best interest. Amazon can only attract workers if it is the best option those workers have.
You have a nice life. Someone comes up to you and holds a gun to your head. You are now about to die. They say "I won't shoot you if you give me all your money".
Suddenly, giving away all your money is in your best interest. Therefore it's voluntary, and by your argument, fair and reasonable and nobody is being taken advantage of because it's all by choice and in best interests. Right?
That is incorrect. By holding a gun, that person has initiated force against you. Initiation of force is a proactive action that requires volition on part of the perpetrator.
Amazon is not initiating force against anyone. If they provide higher than market wages for the workers, they will be violating the rights of their shareholders who will lose money and will be worse off due to the deal. In an industry with as tight margins as Amazon, it can result in flight of capital, loss of shareholder value and layoffs.
comments I haven't verified state that the people had a welfare state income keeping them alive, and that by merely extending an offer of work - at any salary - Amazon causes that to be revoked.
This isn't literally "initiating force" but if it is true then it is very similar in effect to the mugging scenario, and having the mugger use unseen but still present power to "make an offer you can't refuse" is still not a fair and ethical way to egg people to voluntarily enter into contracts.
You're both assuming that offering someone the best option they have rules out the conclusion that you're taking advantage of that person. But that does not necessarily follow.
Then yes, everyone is taking advantage of everyone. My cell phone provider is taking advantage of me because they make profit off of me. I'm taking advantage of them because they spent $1,000,000,000 building the infrastructure so I can use that cell phone. Apple is taking advantage of me by making a profit off of their cell phone. I am taking advantage of Apple by using that phone which they put millions of dollars of research into and shipped to my door.
So we both gain an advantage.
Jack gets a job with Amazon - he is able to afford a color TV and internet at home. Amazon hires Jack - they get their orders shipped to homes on time for Christmas.
Everyone is getting an advantage in all of these situations. No one would ever make an agreement that doesn't provide an advantage.
I assume you're asserting there is a power difference between Amazon and Jack that makes Amazon get more advantage from Jack. This may be true. Amazon, however, has a power difference with customers who ultimately decide whether the billions of dollars worth of infrastructure they are building is worth it or whether competitors will win.
Is it wrong if I decide to not buy from Amazon? Am I taking advantage of them by buying if their product is $10 but not buying if their product is $12?
"Taking advantage" does not mean "getting an economic benefit out of a transaction with someone." It's a moral judgment, defined in terms of conformance with social norms and expectations.
You forget that in Germany, unemployment insurance requires you to not bypass any offers (and you're required to seek work as well).
By "choosing" not to be employed by Amazon, if that's offered to the worker and happens to be their only choice, they "choose" to lose unemployment benefits.
The only assumption is that people will make the decision that is in their best interest. Amazon can only attract workers if it is the best option those workers have.