A building Earth rod is used to ensure that a lightning strike on a house that finds its way into the electrical wiring has a path to ground.
Not in Australia. Ever seen a domestic wiring system that's been the subject of a lightning strike? Blows your appliances to bits, and the power points out of the walls, and fries the cabling insulation.
Wiring Rules of Australia 0.5.41
Earthed - connected to the general mass of the earth in accordance with the appropriate requirements of this standard in such a manner as will ensure the electrical isolation of any defective equipment through the operation of protective equipment. (an earth rod adjacent to the building)
0.5.42
Earthed Situation - a situation wherein there is a reasonable chance of a person touching exposed metal and, at the same time, coming into contact with earth or with any metal or conducting medium which may be in electrical contact with the earth or through which a circuit may be completed to earth.
0.5.64
Neutral (Neutral conductor or Midwire) - the conductor of a three wire or multi wire system which is maintained at an intermediate and approximately uniform potential in respect of the active or outer conductors, or the conductor of a two wire system which is earthed at the origin.
5.8.1.4
Lightning protection system - Lightning protection systems of buildings may be connected by means of an equipotential bonding conductor to the earthing system of the installation provided that the arrangement of the protection system is in accordance with AS 1768. (Not a feature of domestic buildings, only seen on large buildings generally)
Rural properties quite often have only a single wire (the active - due cost of infrastructure to remote sites) supplying the power to the building and the return is via the earth.