> but it's not checkable without some other way to come up with a value which is the whole point - the value doesn't exist independently of what someone else v

> but it's not checkable without some other way to come up with a value which is the whole point - the value doesn't exist independently of what someone else values it for their own purpose. There's no objective measure of value, like the objective measure of some quantity like weight or energy. So the free-market assumption is that everyone is always selfish but rational, and thus would only transact if the resulting transaction is beneficial. in all the cited examples of otherwise, the transaction is fraudulent - someone tricking someone else (which is, technically already illegal, if somewhat un-enforcible all the time).