Housing finance is well established in developed countries while it hardly exists in the Third World. During this period, there were various misconceptions about people who lived in informal housing. In addition, many scholars described squatters and slums as urban cancers, festering sores, and urban fungi. They saw illegal housing as a problem that had to be cleared and replaced by formal housing. Scholars started to see illegal housing not as a problem but as a solution to housing problem .
Standards of services vary greatly.
These include provision of the beginings of a house, what is called a core unit. Most states have left the provision of housing to the market. Accordingly, higher income cities create problems for a wider public and have a greater toll on regional and global environment. Most local governments in the Developed World, on the other hand, have the power and the resources to deal with local environmental problems.