What are the root causes behind "socio-economic"?

There are many. It's an umbrella term for a range of circumstances that tend to be correlated with poverty and social issues.

Low trust in society, few opportunities to improve economic situation, higher prevalence of trauma and ptsd, higher probability of substance abuse, low opportunity cost for going to jail, fewer good role models, worse self esteem, worse education outcomes, worse physical health, higher likelihood of being involved in organized crime, higher likelihood of depending on parallel social structures for safety and protection, etc.

Each can be cause or effect in a self reinforcing network. Picking one single root cause isn't really possible.

One seems to be culture.

For instance, I was caught between a knife fight on a train, because in one hood some of the culture is it's unacceptable to play another culture's music too loud. A Hispanic guy was playing hispanic music quite loud on the train, as soon as it entered a black neighborhood a black guy informed him it was "his hood" and asked him to stop, which then escalated to both pulling out knives.

I have now learned there are certain socio-economic enclaves where culture has dictated that I must not play my music too loud or I will be stabbed to death.