The cat walks at night in the apartment and opens all doors. Adapted to do it as from himself, and himself with his paw.
He is such a sport. It is only in the nature of a cat individual, and family it can vary. If they can live with us, build some social relationship between them, and this appears perfectly natural thing, as the division of labor. This is one of the five main characteristics of social relations. Cats very quickly learn, and things like closed doors, for them no longer obstacles.
Cats are very agile, they are not worth anything to jump to the valve and open it. There are cases when cats have even hooked a friend of Durga to more deftly open the door.