Billboard Living

This is an excellent campaign for Fondation Abbé Pierre, a charity that campaigns against homelessness and poor living conditions in France, and was crafted by French agency BDDP & Fils, Paris.
The idea of the campaign is to raise awareness among both the general public and the government of the unseen, and often ignored, housing crisis in France.
To show the dire living conditions some people put up with, and the little space they have, they presented the adverts in real-size. Posters of 7m² apartments were placed on the floor bluntly showing that thousands of people have as little space to live as a car's parking space. In addition to this, 6m² posters were placed in bus stops, and billboards showed the space of a real-size 12m² apartment were played in the underground.
I think these ads are excellently conceived and it really is a great campaign with a fantastic cause, but it's a shame there is no call to action whatsoever. Therefore, what does this ad accomplish? What are those who are waiting for a bus/tube/walking in the street supposed to take away from this? People will look at these for a matter of seconds, and then move on.