You have to recognize the immense failure of humanity in this case. "At least they got it on video?" Why didn't anyone use that same recording device to contact authorities? Or the bigger question: what was their intent in recording the on-going incident? To have proof of a "crazy incident on the train" to share with their friends? If I see someone being murdered, the last thing I personally want is video evidence if I've not done the responsible thing and contacted the police to potentially prevent the murder.
Sign of the times. Cell phones and social media have conditioned us to believe reality stops at the end of our arms, and everything else is entertainment or something "wild" to be discussed anecdotally after the fact.
Personal anecdote, so take it as you please: a few years back, I was at my local watering hole, and an incident broke out between a very drunk older man and a young woman. Nothing sexual, but they were having a disagreement that had escalated into yelling. Everyone just watched and gossiped about how much this man had had to drink, and yes, a couple people were recording on their cell phone. I tried to stay uninvolved, but eventually the scrum went outside where this man slapped the young woman; that was it. I got involved, and as the damage had been done, tried my best to restrain the man and calm him down. Someone finally called the cops, but while I had the guy's arms pinned to his sides, the woman he slapped and her friend proceeded to beat him. I tried to tell them to stop and wait for the cops, even tried shielding him by turning him into a wall giving my back to the women who were just throwing haymaker after haymaker, but it didn't work; after about 45 seconds, his blood was all over me, but I didn't let him go for fear the assault would turn into a homicide.
The cops showed up, arrested the guy, the women had since retreated to the place they worked a few doors away, and oh boy, did everyone in the bar have shit to say to the cops about what they saw. I was pissed. Everyone had their version of things, but NO ONE actually did anything except me. Even the bartender, responsible for over-serving him in the first place, had her own "so, what had happened was..." take on the ordeal. You know who didn't talk to the cops? Me. One patron went on to testify at the guy's trial a few weeks later, and actually called ME out for not showing up. I had to check him and remind him that it was because of me that it wasn't worse by orders of magnitude. It was open and shut; I don't know what penalty he received, but he was found guilty; I just really wish the other dozens of people I call "friends" would have stepped up and helped me prevent the situation from getting as bad as it did.
This case is just incredible. How does anyone stand bay and watch someone get raped, let alone multiple someones???