I think that you are perhaps missing my point. I'm not saying it would be a good idea to put the world's population in 1.75 billion townhouses(with BBQs and pools), simply that it could be done, that the actual space that would be needed would be the area of NSW, and if roads, parks, schools factories etc are included throw in Qld and leave the entire rest of the world uninhabited.
It's just another way of saying that there aren't that many of us(though that runs counter to the prevailing opinion that we are overpopulated).
BTW, the average population density on Earth, is only 47 people per square kilometer. Not that much I reckon... trouble is that many/most want to live in cities and megacities...
