No the value is decided at the moment of transaction, so that's how companies can accumulate value over transactions that are deemed "fair" by both parties. You

No the value is decided at the moment of transaction, so that's how companies can accumulate value over transactions that are deemed "fair" by both parties. You can decide go give someone $10 for bunch of apple, and the seller can accumulate value from this. The problem here is that one side of the trade does not fully know the value they provide. When you give $10 for an apple, you know exactly what you give and what you get. When you give $0+"your data"+"your ad view/clicks" for "free Facebook service" it's really really unclear what it is you're giving to Facebook and what it is Facebook is giving you.