And they way they are storing and using the data..
Get Real. This is the modern world.
Information is important, and census information is vital for the rational operation of society.
And it is also just about the most "neutral" data out there.
I have delved deep into US census information in studying my family history. As you watch it unfold, it is amazing. In the early days, census-takers went door-to-door to ask questions. In the earliest days, there was the "head of the household" by his white male name, then numbers of males and females by age in decade-length brackets, and numbers of Negroes by male and female.
It took a sizeable chunk of a century for the actual names of each actual person to be recorded, and even longer to include meaningful information about any one of them.
Goofballs who claim to be afraid of "Big Brother" and that he will know where they live are just Luddites who are several generations out of synch with reality. If you really want to get "off the grid" it can probably be done, but not by ignoring this year's census questionnaire.