When we first moved to a Gemeinde just outside of Zürich, my wife and I were amazed to see these cat ladders coming down from balconies. We pass by cats on our walks occasionally, so they definitely use them. It probably helps that we're on the edge of the Gemeinde on a rolling hillside next to cow fields, fields used by sheep, and forest. Very little car traffic. On the other hand, in Zürich city proper I have not seen these ladders as I imagine it is not safe for a cat to be outdoors there.