The problem with the RBE is that the resources on Earth are finite. So you must put a value on them and a money system is necessary. A better idea is the transfer of the file sharing model to the monetary system. You can share the coins like files, through a p2p network.
...but why put value on the Earth's physical resources?
Because the Earth's physical resources are not infinite. RBE is impossible in a finite world. Only air and water are abundant so these ones are free or very cheap. The best thing we can do is to share the money fairly through a p2p network.