It was bound to happen once they started putting advertising on the sides of trains: Coke ads.
Given trains are seen not just by passengers but also by motorists and pedestrians at level crossings, it could be quite lucrative for Metro. One can only hope the money goes into better services.
My guess is we won’t see these on Comeng trains, due to the fluted sides. Too hard to stick ads onto.
But they are putting ads inside the Comeng trains:
And another recent addition is this trial video screen at Melbourne Central Station:
As with (apparently) the ones at stations in Sydney and elsewhere, it goes blank when a train approaches, so as not to be a distraction.
Maybe all this advertising is paying for the shiny new flat-screens popping on the concourse and platforms at the underground stations.