She was so close, off by just one letter.
The rentier class, the landlords who make money in their sleep, own the suburbs and the intown neighborhoods. Private land ownership with its inevitable consolidation means fewer and fewer people own more and more land.
With the growth of population, land grows in value, and the men who work it must pay more for the privilege.
There it was: whenever a population converges around a certain location, the land, of which there is only a limited supply for each location, becomes more expensive to live on; people have to increasingly pay to live on land, and this in turn affects the entire economy.