How and why does a "code of silence" develop within poor communities?

probably, and i'm guessing here, because the poorer a person is, generally the less of a sense of security they have. usually poorer people live in poorer communities where there is less money to spend on security systems. the poorer the community, the less taxes are collected by the local government in that area, which translates to less money for police in that area as well. that then causes criminals to more or less run rampant in that area, which causes property values to go down, which makes more and more people NOT want to move to or live in that area. that causes tax revenues to go down, causing the cycle to start all over again. it's a self fulfilling prophecy that takes a broad "grass roots" effort of many people to overcome.