Yes, this was Kant's philosophy. Moral agents are only people who can use reason. Ethics must be based on reason. If you suck somebody's dick for water, or do anything out of desperation at any level, you are not a moral agent. You are a slave to to your physiology in this case. A person can only make a choice with his mind. Not with the bad circumstances he finds himself in. I would argue that many drug addicts are not moral agents. They don't have agency. They are subordinated to physiology through the drug. They are a slave to the drug. This can be applied to many things. Porn. Do you think a woman makes a decision to get into porn in the mental realm? No, it is because she is desperate. The world picks you up and moves you there. It's the only place you can go.
I could argue for example that Jenna Jameson didn't really choose to go into porn. That wasn't in her heart or head, it was all the world gave her. And then we run into your point. Removing choices is a form of force. Nobody are moral agents really because we are too pussy to follow our hearts. If you make a decision out of shame. Or fear. Those are not legit decisions. Because they were colored by other things. Those are outside forces.
Kant is an idealist obviously. lol. Pretty hard ass on this stuff. He also thought you should never tell a lie. Under any circumstances. Ironically, I find parallels between him and Ayn Rand but with a different spin. Kant said a human being is never an end for another but always an end in himself.
Rand said:
"I swear, by my life and my love of it, that I will never live for the sake of another man, nor ask another man to live for mine." - Ayn Rand
Anyway, point is, Kant would say these people did not consent to work at Amazon lol