The article ends with the comment that the automobile broke the land ownership monopoly by creating suburbia. It took about fifty years to fill out surburbia, but that's been done.
Henry George's single tax plan has been implemented in two cities in the US. One is Fairhope, AL.[1] The Fairhope Single Tax Corporation owns most of the land in the town, including the downtown area, and rents it out on 99 year leases. The ground rent cover all property taxes, plus some public facilities the Single Tax Corporation runs. The corporation sets the rent based, as Henry George wanted, on the most productive use of the land. This encourages development. This just covers the land; you can build, and own the building, but must keep up the rent payments on the land to continue owning the building.
What you can't do in Fairhope is buy land and wait for it to become more valuable. You cannot get a capital gain out of owning land there. So no one can become rich by owning land.