By definition, free trade happens because each side believes they are receiving more value than they are paying. In my example, the manure owner who pays his laborer $15 an hour and the board of directors who pays the Steve Jobsian figure $500,000 an hour both believe that what they get in return is worth more than the money they pay. This is why they enter into the transaction.
>This accumulation of wealth is typically backed by hierarchy and authority structures that maintain that the employer continues to get more value out of someone's work than the employee(s) participating in that work.<
And from the other side, the laborer who exchanges his time for $15 per hour and the Steve Jobsian figure who exchanges his time for $500,000 an hour both "continue to get more value out of" the money the employer is paying them than they would otherwise get out of their other options. Again, this is why they agree to exchange their time for money.
Again, this all boils down to supply and demand (plus value). If there are millions of laborers that can perform any task, the price to perform that task will always be low, no matter how much value the task ultimately generates. (I say plus value because, even if you're the only person in the world that can do something, if nobody wants that thing done (i.e. no value is created) then no one will agree to transact.)