Slums are also in cities like "New York" and "London". No government in the world has enough resources to acquire land, construct buildings and provide other required facilites to slum areas.
I was involved in a serious dicussion on slums. The outcome of discussion was nil. But what I came to know was that it is impossible for any government in the world even to provide 50% of their slum proper housing facilities because land is limited for rapid growing population.