If energy is an "abstract concept", if you buy batteries for your flashlight, but when you get home you find that the batteries are dead, you don't have much of a case to demand your money back.
1) The value of the money is an abstract concept as well.
2) I'm not paying for an abstract concept, but for batteries in a certain state, which is quantified by an abstract concept.
Abstract just means it can be applied to different objects as a measure. It is not different from length: you can buy a meter of string or a meter of cable. But you pay for the string and cable not for the concept of length.
When making business, both side must agree on the concepts of value they use.It's no one else's responsibility that you have decided to form a particular concept.