Our census does not necessarily mean concensus in its use
"...to offer it to just about every arm of government for cross-referencing..."
and
"while noble in aims, data matching across government is worryingly pervasive."
Remember folks, this is the Tax Man talking to CentreLink talking to your local council talking to.... without any oversight worth a damn. You get the point.
This is a data analyst's wet dream, and will be hotly pursued by the likes of Scott Morrison (he just happens to be the current one - I doubt Labor would be any different) using it to 'catch' all the people who allegedly defraud the country of zillions each year.
The fact that we all give "away vast amounts of personal data by joining social networks..." isn't really the point. We do this with (hopefully) our eyes open, and for some small anticipation of a return. EG: You get FaceBork for nothing because it 'helps' you keep in touch. You accept that you're the product. It's also (unless you've got huge resources) not all in one place or easily accessible to Big Brother.
In the case of the census, you're giving all this info to the Gov't gratis. The only return for your average punter is the heart-warming feeling that you've helped the country in its future planning, or that your great x 3 grand kids get to see you as an entry on ancestry.com next century.
"...the companies you gave it to show they have few scruples..." Very true, but I'm still at liberty to remove my association with them at my convenience. I fail to see how I can remove my association with Her Maj's Oz Gov't without removing myself permanently from Australia.
So... This time the census (and hence the Gov't) is going to keep your name(s) and address instead of anonymising the data. In those immortal words, "What could possibly go wrong?"
Come August 9th, I may find a quiet beach somewhere that requires at least a day's walk from the nearest road and set up camp for a few days until it all blows over. The buggers will probably still find me.
Name: L. Skywalker
Religion: Jedi