@ares, I understand the confusion.  I initial thought similarly.  However, it goes back to the idea of white-listing vs black-listing or children add from their parents or delete from their parents. We chose that children inherit from the parents and can add to them.  Therefore, B1 (Brno) inherits from A (Czech Republic) and thus can see what's in A and add to it.  

The reason for both directions to do fix the awkward case (that I originally demoed), where Israel/Tel Aviv/Rack7 shows all domains but Israel only shows very few domains.  Intuitively, it should be opposite.  If Israel is current location, I should see all under Israel, wheras if I'm in "Rack7", I should see everything that Rack7 inherited PLUS its children (if any). Thus, both directions.