Many things factor into the value of a good, including where it is and who owns it. If the bartering involves the apple and the potato trading places it’s easy to see how value is created, as the value of a good depends on its location and transporting it to a location where it is more highly valued creates value. (Otherwise transportation as an industry could never create value, in which case, why would anyone ever transport anything?)

It’s more rare that ownership will factor into value, but it comes up sometimes. An example is when the whole of something is worth more than the sum of the parts, like buying the last missing piece of a city block so that you can put a full-block development on it.