This photo was taken in almost darkness, yet it looks to be light. I think the blurriness tells you the camera was struggling with light.
I think the tram shelters work like this. A private company erects them, maintains them and cleans them. They sublet the shelter advertising to another company who maintain the ads and all do a fine job, I must say. It costs tram passengers and councils nothing. All win.
But when the advertisers start taking over public footpaths with their ads, I start to get concerned. Thankfully it has now been removed.
Edit: The mat may have gone, but the sticky stuff that held the mat in place has not gone and dead leaves have stuck to it. Very attractive.