People are reluctant to engage in social interaction with strangers.

 

  The reason why people are reluctant to engage in social interaction with strangers is that people don't feel competent or qualified to help. With the development of science,especially Internet,people tend to be difficult to communicate each other,because people recently reduce their time to communicate in reality and increase their time to communicate in Internet. This incident makes people lose their self-confidence to take communication with someone,furthermore, people avoid talking with someone,especially with strangers. This less communication also cause their losing competent or qualified to help strangers,and they also avoid being spoken by strangers and  involved in some event which is not their business. 

  In addition to the less communication, the development of science has reduced a chance to be asked to help by someone,because people are becoming to do almost all of things by themselves with this development. According to this decreasing,people are losing experiences to help someone,and the less experience decreases their abilities and self-confidence to help someone.

 So,people are reluctant to help strangers because of their less competent or qualified.