I'm always confused by these kind of pictures. The 'developed' spaces have apartment towers and dense construction - many more people appear to live there per acre. If land is at such a premium (and the towers seem to indicate this) then how on earth does the shack-dweller afford so much land (relatively) for their very-much-lower density housing? Sure maybe 20 people live in a shack, I understand that, but in the sa…
Price per square m/ft is much lower in the slum than in the gated community.
If you couldn't aford a place in the gated community, would you use that money to buy a place in the slum? Or would you try elsewhere?
The problem in general is not absolute lack of space for building (except islands like Japan, ...), but lack of place to build in desirable locations.