During the 1940s and 1950s the "anti-labour" (and incidentally, anti-Labor) parties finally got organised, and started whipping their backbenchers. From the 1940s Australia has had a well developed party system with fairly rigorously controlled party internals.
Part of the reason for the development of rigorously controlled parties can be seen in the central division of Australian politics over the issue of labourism. The nascent labour movement failed to gain absolute and complete control over early socialist parties, and the requirement to keep our friends in the AWU inside the tent as much as possible led to a fairly vigorous discussion on binding parliamentarians within the Labor party and the Labour movement. Movements to the left of labor within the labour movement, such as the CPA or the Greens exercise even more control over their parliamentarians than Labor has or did—in part because of the criticism of Labor's failures here.
Prior to 1940 the anti-labour parties were fairly disorganised. They usually formed as a result of a split within Labor, with right wing members of the labour movement walking outwards towards the nationalist and imperialist right wingers, taking votes straight into the hands of the Country Party or the urban bourgeois party of the day.
Menzies stopped all this. His new party was well formed and organised. Menzies modelled a fair bit of his party organisation on Labor, but not so much as to offend anyone, and only the bits that worked for an urban bourgeois party.
Dixers are a result of the well-bound and well-founded parliamentary parties, their monopoly over Australian parliament, and their division over the anti-labor issue during the 20th century.