Kibera slums and Highrise Estate in Nairobi are divided by a wall. Those in Kibera slums live well below the poverty line and make do with a meal a day. Those in Highrise are a bit better off and can afford to store food in their fridges and discard if it goes bad.
It is not the wall between the two residential areas that stops those living in the slums from raiding their wealthier neighbours. It is not the gates or the watchmen there. As a group, acting with a common purpose, if they decided to scale the walls and the gates to raid their wealthier neighbours nothing would stop them. The other slum dwellers would pick up the trend and would do the same to their wealthier neighbours.