Confession in succession...

It’s Sunday, so let me take you inside a church today. I found this sign in Saint Sulpice and I thought it was really odd. It looks like there are so many people willing to confess that they have to organize a queue/line or something. Are people in the 6th arrondissement big sinners or what?! Anyway, as you may already know, among the Christians, only Catholics need to talk to a priest to be absolved, the Protestants ask directly forgiveness from God. And from what I could see on the web, no such thing as confession exists among the Muslims or the Jews.