Why don't have those, in Italy. I believe it's something from the arabic culture mostly, if I understand correctly. We have similar looking wooden "over the wall" things but they were used to create bathrooms in houses lacking those, when they became common. But the shape is different.

now when you mention it, i recognize i never seen those in italy. until now i thought it's a common thing in meditarrean/iberian peninsula stuff. we even have some in prague, but it's really rare.