But by Australian standards the Liberal Party (Canada) corresponds to the Left of the Australian Labor Party (ALP). None of the past two ALP Prime Ministers are leftists (Bob Hawke and even Paul Keating are both pro-American). On the right the Liberal Party and National Party are either as right or even more conservative than the Canadian Conservative Party.
On the side Australians consider as political fever swamp aka the Left of ALP, they have the Australian Democratic Party and Green Party. Both are equivalent to Canada's New Democratic Party and are nutty left-wing by Australian standards. Australians largely shun these two parties - they get around 4-5% of the vote. None of these two have never reached outright majorities alone st state level (the best result the Greens and Democrats could get is at the most left-wing Australian state Tasmania. But even there they could only get around 18% of vote)
I wonder what makes Canada's politics far to the left of Australia, let alone the United States's?
I guess the difficulty in comparing lies in there being so many different axes along which to measure conservatism. There's conservatism in amount of spending, conservatism in broadness of spending, conservatism in taxation (three different things); there's conservatism in moral terms and conservatism in racial terms and conservatism in doing-whatever-Bush-says terms. It's possible to be at a different place on all those scales.
Is Canada further to the left than Australia? Not knowing much about Australian politics, and going just on your description, probably somewhat. Through the 1990s, the Liberals were conservative spenders (pushed that way by the Reform Party), but didn't restrict the broad reach of Canada's social safety net. Nor were they conservative morally or do-whatever-Bush says conservative. The Tories of the 1980s, on the other hand, were not at all conservative spenders, but were definitely do-whatever-Reagan-says conservatives.
The Reform wing of the new Conservative Party is to the right on all scales (though certainly not as far right as some of the European nationalist parties on the racial scale). But how much power it'll have in the new Conservative Party is hard to say; certainly if the party wants to keep getting elected in Canada, it won't have much, just enough to keep Albertans and the interior of British Columbia happy.
(There is, however, a growing band of suburbs around Toronto - the "905 region" - that votes to the right. They drove Reagan-ite conservative Mike Harris to premiership in Ontario in much the same way that the growing suburbs (and growing suburban anger at high taxes) in California in the 1960s brought Reagan the governership there.)
Anyway, to your question: What makes our politics so far to the left?
Hells if I know. Maybe higher rates of urbanization versus suburbanization? City people tend to vote left. Maybe a much less visible underclass? Social programs are much less likely to be supported if the recipients are very different from the payers. Maybe the eloquence of Tommy Douglas and the savoire faire of Pierre Trudeau? Maybe because we were founded by alcoholics and bumblers instead of slaveowners or convicts?
I dunno.