Advertising

I guess advertisements in and around public transport vehicles is nothing new.   When I was young, there were neat rows of advertisements lining the ceilings of trams, and in frames on the walls at the end of the red rattler carriages (although I preferred the photos of scenic locations that were also placed there). 

Now we see the outside of some trains featuring prominent advertisements, but once again this has been happening on the trams for years.  

However, advertisements covering the inside of the train doors seem be a relatively recent development.   Perhaps the logic is that you really do have to look at the door at least for a short time during each journey?