I also worked as a canvasser in 2019 and 2020 for the US census and, while we were about as thorough as you could reasonably get, the whole operation made me somewhat skeptical of official statistics in general. 2020 in particular was a bit of a disaster due to the pandemic and when the statistics were published, a bunch of mainstream news outlets published stories about certain areas experiencing "population decline" and all I could think was that those were actually the areas where the census didn't manage to count everyone.
If for example you have poor compliance with the law then the law is mostly useless (in the US you do have to update your ID in 30 days, but huge numbers of people dont).
And that doesn't count if your country has a huge undocumented population, like some places in the US do.
"Wow, why are the roads wearing out twice as fast as we expect?!"