eXeCuToR vs Denminator

But rather, they are selling their labor, not themselves.

I agree, but let's consider whether labor can generate income, or whether a person can without labor. Only together can they. He is selling his labor, the experience of many years, but by working, he is selling not only his labor but also himself. Let's look at an example: A surgeon performs serious operations. This is hard work. Then, he accidentally kills a patient. The doctor is responsible for his patients not only to them but also to the state. He receives money. The state pays him for his labor.

STATE<>WORKER

Next, an example of "selling." I put the word "selling" in quotation marks for a reason. We "buy" friends, but it doesn't necessarily involve money. It can be charm, manners, attitude – a kind of currency. The way one approaches a person is their own kind of price.