because money is the identity of a country, other than as a tool to transact. maybe you are thinking, why not get paid using gold, or diamond? because both are assets that are subject to change. so it would be better if using the money.
no I am thinking exchanging time for time, using resources as your money supply is not to smart as your country could use those resources look at the penny it cost more to make then its even worth we had to revoke them in Canada