As a result of the World Fair in Antwerp in 1930 and the expected increase in passengers, all seats were removed from a number of trams (also for the staff...) and only standing places were available. This is what was written on the tram (in both national languages at the time). To my knowledge unique: I cannot find any other passenger tram without seats. Of course, the trams (there were several) got their seats back after the exhibition.

Author unknown, photo from my collection.