Why people are reluctant to help for strangers?

  According to the task,I think the reason why people are reluctant to engage in social interaction with strangers is that people's lives are busy,they are often too rushed in the megacity.Or sometimes people fear that they will be asked to give additional help after the initial request.There's no denying the fact that in the big cities as New York ,the life speed is really fast,people are not capable of helping any time and where. They have work to do ,people may are too rushed by theirs job or family etc.Strangers are not people's family or friends,Therefore ,they might don't have time to do the additional help after the initial request.In this respect ,we may as well say people were changed by the living environment.From my point of view ,it would be better if people could give fair respect each other in the public aid.