Deviation from norms in childhood development within a child's society or a crisis within a society can hinder emotional development. Many places differ. Two children can experience similar childhoods of struggle, but if those around the struggling child aren't experiencing similar events, then a cognitive dissociation from those around them may occur; essentially, preventing them from developing a similar theory of mind that enables them to connect, empathize, and simply function alongside others within their group. This is why we can find mentally healthy children in undeveloped nations undergo grueling experiences, while children in developed nations can experience only a fraction of that trauma, yet can begin to deviate both emotionally and cognitively from norms. In other words, when there is extreme inequality concerning basic survival and decency in a nation, children suffer. I might also add that there is no set definition on what constitutes maturity. It's a matter of perspective, I think. Being from an individualistic culture myself, I would say that I think that people from honor-based cultures are emotionally immature as a whole. The majority of the US prison system is filled with people that were raised in an honor-based culture within the US. I think that cursing and screaming at your boyfriend in a parking lot, as if he's killed someone, then recklessly speeding up near my child & I is incredibly emotionally immature. But, many in the US would disagree with me, and say it's perfectly normal to them.
Suffering and hardship would be a primary cause for emotional immaturity, not an outcome. Maturity from trauma is actually not typical. Sometimes, it breaks people. You have to remove the stimulus and cause of suffering firstly. The conditions thereafter would determine whether or not those learning experiences can be utilized later on. But, it is a very painful process and requires a person to transcend to a place of forgiveness and acknowledgment. The price is sometimes so high that they still cannot fit in when they do begin trying to catch up.