The ABC and SBS are basically government funded channels. They are supposed to give everybody in the country some form of Radio and TV service. 'Commercial TV'

The ABC and SBS are basically government funded channels. They are supposed to give everybody in the country some form of Radio and TV service. 'Commercial TV' are the advertisement-funded private TV Channels originally 7, 9, and 10* (but now also include the later extra digital channels run by those companies). Obviously, some outback areas of the country are not commercially viable, so their Radio and TV services are very likely limited to ABC and SBS. * Channel 10 was originally aired on the Channel 0 frequencies back in the 1960s. That frequency band was required for some other services, so Channel 0 TV Stations were moved up to Channel 10.