It's not like people always keep their residence up to date though. If you are still able to receive official correspondence at your previous address (e.g. parents' home), why would you bother changing it? Even more so across a border -- it's trivial to have multiple residences at the same time and they are not guaranteed to be unique, nor are they necessarily considered tax residences. That is, you can be tax resident in a country where you don't have permanent residence even if you have permanent residence in another country.
