The census laws in many countries protect access to the actual raw data until at least a few years and usually a few decades after the people in question are de

The census laws in many countries protect access to the actual raw data until at least a few years and usually a few decades after the people in question are dead and sometimes there’s even blanket rules on accessing anything more recent than 75 to a hundred years ago. So even the governments with extensive historical records tend to follow similar rules to the ones you mention about archives access.