>Despite the obvious difference between physical things and ideas, we often treat them similarly (specifically, we treat ideas like physical objects). And perhaps that would seem a bit strange if we weren't so used to it.

ok but they way that we treat them the same are both constructs, we don't treat them the same in that if A has the idea you can't have it (in the same way that if A takes the bite of bread you cannot have that bite of bread), we treat them the same that if A has the idea they have a right to profit from it by selling you the idea in the form of a book etc. just as if A has the bread they have a right to profit from it by selling you a bite. And you don't have the right to take the bread from A just because you can.

As noted while it is physically impossible for an object to exist in two places at the same time it is the social construct of ownership that we transfer from physical objects to non-physical objects.