[mrchicity]

Public transit in major cities is a set of complex queuing systems. If a station is slower getting people out, they will crowd on the platform and create "back-pressure" on the entire system as the crowd causes incoming trains to take longer to unload, people will see longer queues to enter the system so they'll be marginally more likely to take a cab or abandon their trip.

So some of the 3000 people were literally standing on the platform, but many of them may have been new customers or time-shifted rides that didn't even exist before.

All of this seems like a very micro optimization to eek out efficiency in peak throughput. The bigger macro problem is that transit is centered around sharp peaks due to inflexible work/life schedules. Moving everyone in London or New York around is tough enough, but doing it in a few hours each day is a nightmare and you have to massively overbuild infrastructure.