This seems vague and without enough context

There is a law in physics that says energy/matter cannot be destroyed at but only converted from one form to another (with matter being a form of energy according to E = MC²). In that way, this idea of "equivalent exchange" might be somewhat grounded in reality. But it is hard to see how that applies in any way to 'giving' and 'getting' even considering how vague those words are. In a practical sense, even energy is always lost as a result of the inefficiency of machines. For instance, you have to give a lot more energy in calories and peddling when riding a bike than is outputted in the movement of you and the bike to your destination. In other senses, such laws of physics seem even more irrelevant and the speculation of "equivalent exchange" seems even more clearly false. For instance, the economy is full of instances where someone gets scammed out of losses and profits and people getting way or more or way less than what they bargained for.