It seems expensive at around $4-5 per person per year! I think a satellite could gather useful population information based on a year of observing people entering and leaving their homes. I also wonder why the government needs to account for everyone in America? Can’t it just account for taxpayers who voluntarily work with the government system at the state and federal level?
The census collects information on everyone because that's what the Constitution says it has to do. There's a bit over 200 years of case law arguing the specifics (e.g. how to handle the "Indians not taxed" exception), but in modern times it's interpreted to mean literally everyone.
