One can hold open the doors on a waratah to let your friends run for the train. But not on tangaras.
Yeah well don't, thank you. If your friends can't be on the platform 5min before the train is due - like the other 99% of ordinary commuters - they can just get the next train, instead of being selfish and delaying the train for everyone else on board. Why should those people have to endure a late service just because one or two tools can't get their act together?
And as Raichase has explained above, these things have a domino effect. Imagine if that happened at, say, every third (or more) station between Hornsby/Penrith/Campbelltown/Waterfall/etc & Sydney? One seriously late service, a lot of peed off commuters, and some peed off station staff & train crew.