My impression is that the Australian Labor Party does win some rural seats. Possibly this was more common in earlier times.

For example the Labor Party is very competitive in Tasmania, the state which has its population least concentrated in its capital city. There is a state poll which suggests Labor may well win all five seats in Tasmania.

The Labor Party has held the most rural electorate of all, the Northern Territory seat (in the days before the Territory was divided into two electorates, one in the Darwin area and the other covering 98% of the area of the Territory).

Queensland, the only state where the Nationals are stronger than the Liberals, was a very strong Labor state in the first half of the twentieth century (indeed even as a colony in the nineteenth century it produced the world's first Labour government - it only lasted a week but still). Of course a lot of that support was probably contingent on Laboutr support for the White Australia policy and evaporated when the Whitlam government modernised the immigration laws and started paying attention to the problems of the Aborigines. The infamous Sir Joh Bjelke-Petersen led an entrenched Country/National government in the 'Deep North' state, which with the aid of a pro-rural gerrymander was in power for decades. In the end it required a Labour-Liberal coalition (a concept almost unthinkable in other states) to break the National hold on the state.

However the main support of both the Liberal and Labor parties is in urban and suburban areas, with the Nationals probably in a very slow, long term decline as the percentage of very rural electorates declines.
In 1922 the Country Party won 14 House seats out of 75. In 1949 when the House was expanded to 121 members the CP won 19 seats. In 1984 they won 21 out of 148 seats (by which time they were the National Party of Australia, which was a re-branding attempt to appeal beyond the rural core vote). In general their percentage of the House seats has declined over time.