Inertia. Census questions are a slow moving beast, and getting them updated is extremely difficult. The question on volunteerism in this year’s census was a request from Peter Costello, three censuses ago. The Australian Bureau of Statistics could not afford to spend the money to get rid of it.
There is plenty of cowboy stuff to blame the ABS for, but if they hadn’t been defunded and rudderless, they wouldn’t have gone cowboy to begin with.
That inertia is in play widely. People noted with dismay the lack of an intersex option on the census. State governments have been more proactive: in the ACT it is in fact mandated to offer intersex as an option in any government survey; and the data standard I help manage in the Australian school sector has been updated to include it.
But the federal bodies in education have not updated their data collection manual yet. And in fact the parenting role question has been a bone of contention between the state and federal bodies in education, for the same reason. Federal bodies are interested in establishing mothers’ role in encouraging education. State bodies have little interest anymore in differentiating fathers from mothers in their data collecting.
So it’s not really that they’ve chosen to exclude, it’s that they haven’t gotten around to updating.