[pjc50]

It's not a mobile phone thing; I got punched in the face on a commuter train 20 years ago and none of the crowd got involved then either.

It's partly bystander effect ("I'll leave it to someone else to intervene") and partly a very real fear of the intervention going wrong. Maybe you get stabbed. Maybe the police get involved and you end up with an assault conviction and consequent expulsion from the middle class. Maybe the scene isn't all it seems (setup for robbery, or domestic where both parties turn on the intervenor).

Commuting and the mass-population city kind of relies on us forming the habit of studiously ignoring one another, and it's a hard habit to shake in an emergency.

[Cthulhu_]

There have been quite a few stories where people that intervened were themselves charged with assaults. There's been burglars breaking into houses whose owners were charged with invasion of privacy for having security cameras in their own house.

Taking justice in your own hand - helping people out in a violent situation - is frowned upon and discouraged. Perhaps even moreso in the US, where it's much more likely that people carry guns and people - bystanders or those directly involved - get killed.

But as I'm sure is mentioned elsewhere, the main causes of inaction are the exceptionality of the situation (despite what the media wants you to believe) and a group mentality (nobody's doing anything, so why should I? Alternatively, maybe the group is seeing something I haven't, could be dangerous)

[josephlord]

> There's been burglars breaking into houses whose owners were charged with invasion of privacy for having security cameras in their own house.

I don't normally do this but extraordinary claims need evidence. Citation?

[FireBeyond]

I've never heard of an invasion of privacy suit against a homeowner, and I couldn't imagine it succeeding. What reasonable expectation of privacy do you have when being in someone else's home without consent?

And when you read more on many of those assault charges, you realize there's more to the story. Some I've seen:

Man's alarm and CCTV system alerts him to intruder. He doesn't call 911, but plans ambush, injures burglar, and only then summons help.

Man alerted to burglar as burglar is leaving premises, shoots burglar in back as burglar has left home but not property, attempts to claim he felt his life in danger, even though the burglar had not discovered him, and was in fact leaving the premises.