So for example a high voltage power line is planned to be installed between point A and B. Now, probably some land has to be bought. But maybe not everyone sells land. So maybe land is seized, for the good of all. But ... is it really for the good of alL? The government MUST know beyond a doubt it that line is really worthwhile for the entirety. They need hard planning numbers.

There are numerous scenarios available where a government --- or even private companies --- need dependable statistical numbers to do planning.

And that is e.g. the reason why in Germany businesses have to wire lots of data to a government statistical bureau. We all can then get the relevant statistics out of the 16 state and the one federal offices of statistics. Or (e.g in Germany) the "Bundesnetzagentur" uses it base decisions about the grid on it.

Or private people need to register (cost free, via web, at least in Germany) their balcony solar. Compared to what the businesses have to tell this is almost negligible. It only makes sense due to the sheer number of balcony solar installations.