It's really like this

This is a (camera phone picture of) an ad from the train station. The bottom (not shown) admonishes people to let people off before getting on themselves.

The thing is... it's really like this.

Every day all day long there are really people trying to get out of the train who are blocked and pinned by the people trying to come in. As weird as I feel stating something this obvious... it is purely to the benefit of the people trying to get on the train to have the people on the train get off first.
It's sort of like everyone is being scouted for some real life version of Football (yes, the American kind).

And once people have gotten on the train. Bang. Full stop. They know that there is space in front of them (i.e. deeper in the train), that there are twelve people trying to get on right after them. But they're on the train and all is good with the world. They seem surprised and confused when everyone right behind them continues to get onto their train; and certainly don't try to get further in the train or otherwise out of the doorway.

Actually the people on the train are -zero- help too. In the face of five or ten people who are trying to get off people will just stand in the doorway. The gentle nonverbal nudging that works so well in places like Japan is met with a glance and a frown. Loud verbal admonishes that you're getting off, you're really sorry to trouble them, if they could just move a little bit you could get off and they could be on their way are met with a grunt and a quarter-step (often deeper into the train and the people who are trying to get off).

Eventually you do reach some sort of equilibrium.
A snaking congo line of people slowly and agonizingly works it's way through the train before forcing it's way through the slavering horde of boarders fighting desperately to be the first one on. Everyone's unhappy, nobody's going anywhere and you're left wondering if trains were only recently implemented and people still haven't really figured out how they work.

There's no open seats by the way. It's not like they're dashing into a car to get that last precious vacant seat. [cause if it were then that would be totally ok wouldn't it? ed. I'm just saying it would be understandable. you mean you'd be deploying the forearm shiver on grannies. ed. I like sitting down. Anyway there are no seats. That's the situation we're talking about.]

[it's a good thing you brought this crisis in public transportation to the attention of the internet community. action must be taken. ed.]