It is mainly artificial. A bit like the zoning codes in the US I think. There is property where you can build a proper house and live there (requirement is, th

It is mainly artificial. A bit like the zoning codes in the US I think. There is property where you can build a proper house and live there (requirement is, that there is infrastructure, like water and electricity). Then there are gardens, where maybe a small cabin is allowed (but you may not officially live there). And then there is everything else, where you normally cannot build anything.