The main purpose of the census is to establish a count so the apportionment of Represntatives to Congress can be determined. As with all the government, it has grown to meet other "needs".(posted 9622 days ago)When the social security numbers were first given out the government assured the people that they would never be used as a national identification number and were only to be used for social security determinations. Try doing something without one now.
Income tax information was initially "guaranteed" to forever be only used by the federal government for income tax purposes. Now it is shared any state that asks, and is routinely used for nontax purposes.
There only needs to be a small change in the law and your confidential census of this year is next years public information.
There are many things that are given by the government to state and local governments based on the count in the census. Of course if the federal government would not take all that extra money in the first place there would be no need to send it back, after deducting a hefty administrative cost.
You lose voice in the government if you don't fill it out and you loose privacy(especially with the long forms) if you do. Sound like th ecurrent state of the American Government.