It's game theory and herding in effect. We all know it'd be most helpful to the group to abandon our luggage and exit single file. We also know no one else will

It's game theory and herding in effect. We all know it'd be most helpful to the group to abandon our luggage and exit single file. We also know no one else will do it. Plus, we witness examples and use those as justification for similar behavior. There have been studies done that show if you're in the middle of a crisis with bystanders, it's important to single them out and call for their direct responsibility: "You in the green shirt, call the police now!" Otherwise, responsibility distributes evenly among the group with no one player having enough impetus to affect change.