That is a product of the dire straights that have always existed in the inner cities, especially after the end of the Civil War.
What you had were immigrants and after the war newly freed slaves that were completely uneducated and had nowhere to go, so they all flocked to the inner cities to take whatever jobs they could find. Being largely illiterate, most were taken advantage of and paid slave wages (literally in many cases).
What this led to was a situation of mass dire straights, which gave birth to mass crime to make ends meet.
It has never, ever changed. To this day, those born into poor families in the inner cities are stuck in the same trap that their fathers fathers fathers were born into. Until that is changed, it will remain the status quo of inner cities.