And as far as safety is concerned, when every seat is full and there's already very little seat-to-seat distance, the aisle is crammed with people face to back with nothing to hang on to, and the vestibules are all full to the point that people are standing with nothing to support them if the train brakes hard, that is a crammed train. Dangerously so -- indeed, often illegally so.
And this is quite normal, routine and unexceptional at commuter times, and that is not talking about the underground, where it is routine to be packed in to the point that someone's nose is against the window (mine was, yesterday).
I'm sure there are trains elsewhere that are worse. There's nothing I can do about that; it doesn't really change my observation.
(I'm not sure there's a really good point about gratitude here, either, when the people paying for these services where they don't get a seat have to take out substantial loans to afford the annual ticket, whereas you can travel from Cape Town to Johannesburg, with a sleeping car berth, for about 20% more than the amount it costs me to travel an hour into London at off-peak times. But that's a separate point.)
That was the Metra BN line in Chicago when I lived there, at least the rush hour departures at around 5:00pm. I was on a train so full that I could not even fully get into the vestibule, I had to push people in with my body so the door could close behind me. Many times the CTA trains were similarly full.
Generally speaking and especially when compared with trams or buses, mainline trains don't really do "hard" braking, though. Though I concede that the jerk of coming to a full stop with the brakes fully applied (during regular braking drivers and/or the train control system will ease off the brakes before stopping) may be somewhat borderline in terms of keeping your stability.
Also try the Tube in London’s rush hour - more like stuffed in than even crammed in. Full armpit-in-the-face experience.
I've also hung out of Cape Town trains because that's the only way to get on - all doors forced open by commuters so we can get a few more people to work.
Sincerely, from someone in the third world who has taken UK public transport. You don't.
I don't say this to disparage your message, but hopefully to give some gratitude for the nice things you do have over there.
I found it most amusing how people would get antsy and annoyed when a train was more than 5 minutes late in the UK. For years of me taking South African trains, if there was any delay worth being mad about, it would've been after 2 hours had passed.