You said it like city slums are problems. To me it is not, it is a sign of "organic" growing cities. If I am allowed to take a startup metaphor. Slums are just tech debts. And apparently you didn't understand what the policy in the article means. Instead of enforcing "safe labor practice, minimum wage, vacation days", they simply enforce an upper limit of population. It is like to guarantee productivity you enforce your employee to produce x lines of code every day. Of course it won't work. And you just went way off topic.