My flat has the shape of a big rectangle, and all the corridor is lined with built-in closets. It's one of its major positive aspects.
In my experience, many flats have 1-3 built-in closets, but not always in a bedroom.
And I think that what allows the walk-in closets in American houses is linked to the size of the houses: American houses globally are bigger in size than Swiss ones, simply because here we have less space available.
This user would like to thank Mélusine for this useful post: