They have always had far right wing nutters running the place.
Their past PMs, Faser, Howard and Abbott could be hardly viewed as liberal and centrist at all. Remember that Fraser cut Medibank and ended universal health care, Howard tried to give us Work Choices that effectively took away all rights in the workplace, and then there was Tony. Turnbull showed promise and he was voted in on the belief that he was progressive and moderate, but not so.
While Labor Governments from 1972 have not been perfect and made some poor decisions, racked by internal division, they did restore and strengthen Universal Health Care with Medicare, did modernise our economy by deregulating banks, tried to improve workplaces and productivity with the Accords, kept the economy moving though the GFC, and many other things.