Mistero at the foot of a door

We just moved into our new condo and observed that another condo on our floor had a “thing” along the foot of their door: (image at right below), which isn’t present at the foot of our door (left image). You can see this by comparing the depth of the silver metal plates at the foot of the two doors: Note that the “door to carpet” depth of the silver metal plate at the foot of our door is greater than that of the other condo’s door, because the plate at the foot of the door on the right is partially covered by the “thing”, which seemed to be like a roll of fabric.

First, what is the purpose of the “thing”?

You may know, or guess, that cloth rolls like this “thing” are often used in households to cover a gap at the foot of a door so as to prevent cold drafts from entering the room……but such draft-blocking rolls are placed at the foot of the door on the inside, not the outside, of a room!

So this is the real mystery…..How could a person place a draft blocker on the outside of the door without disturbing it when they open the door to go back inside?

What goes on here?

If you have an idea, send it to Grandpa via the Mailto button. If not, find out by pressing the Soluzione button!