To the people squabbling about history, there is indeed a history of countries collecting information for perfectly innocent reasons.
There's also a history of countries changing the use of the information the moment the shit hits the fan.
The perfectly innocent 1930s censuses of France and the Netherlands were seized on by the invading Nazis to locate and round up Jewish people. The Netherlands had particularly accurate, detailed censuses which contributed to the high detention rates of Jewish people there, despite quite heroic resistance by the Dutch in general.
Edwin Black set this out in great detail in IBM and the Holocaust.
(IBM, because the punch card machines bought to process censuses turned out to be jolly useful for arranging the movements of hundreds of thousands of people, selected for their religion and sometimes for their skilled occupations. Helped the trains run on time, too. The machines were also installed in the concentration camps.)
So deciding whether or not to answer census/monitoring questions really is a question of what you personally guess that data might be used for in the next decade or two. Including if it's leaked, stolen or sold.
And I'm sorry to those bored hearing about what the Nazis did. They happen to be a well-documented and local example of the nuts and bolts of how governments can use data, when so minded. As a PP said, other examples are available.