The Pali of the second precept runs like this;
Adinnadana veramani sikkhapadam samadyami. (spelling ? )
Adinnadana means, to take the not given . Which is often interpreted as the not freely given.
So the whole thing is rendered, " I undertake the rule of training to refrain from taking what is not freely given ".
This is usually applied to material goods, money etc. But some commentators would include other peoples time and so on.
It is not a matter of moral relativism. In other words the kamma-vipaka from stealing from the rich is no different from that incurred by stealing from the poor. The vipaka arises from the intention of taking that which is not freely given.