I fully support this suggestion!
For me, having more NPCs already makes a big difference, because a busier platform instantly feels more alive and atmospheric. It adds more immersion and that special railway romance.
In addition to simply increasing the number of NPCs, I’d like to share some of my own ideas that could further improve realism:
NPCs interacting more with each other, such as meeting and saying goodbye (hugs, kisses)
Late passengers running to catch their train
Passengers stepping over the yellow safety line, forcing the driver to use the horn
People using level crossings and pedestrian crossings, with some occasionally breaking the rules
Animations of passengers pressing the door open button or opening doors manually
Trainspotters taking photos of trains
Families traveling together
These details are not part of the original proposal, but I believe they would significantly increase immersion and make the world feel much more dynamic and realistic.