@ Wolfgang
it's less costly to bring just two wires in rural areas with light loads. Since the wire size and insulator size is pretty much fixed, a third wire merely carries cost. (Transmission is different and so is distribution in densly populated areas)
On the other hand, it must be more expensive to supply 1 x 100A @ 230V than 2 x 50A 230/460V or 3 x 40A 230/400V if you already have a split phase or 3-ph LV network. Somehow, I get the feeling that thinking out of the box isn't encouraged in utilities.
