Mark Twain was rather silly because land value's do not work that way.
There is plenty of land that is unused in the world, it is just having land that is in demand that can be the problem.
Where the world population is blessed is, we have technology now that can make formerly useless land for cultivating crops, into ones that do grow crops. Never in my life did I think it would be possible for Maine to grow tomatoes all year long, but that is indeed happening now. Plastic greenhouses have evolved to the point where the cost of creating an environment year around for tomatoes is possible on a commercial farming scale in Maine.
Amazing.
But it can also work in reverse too. A lot of large tracks of land are up for sale near me because the cost of property taxes has increased in time to the value of a forest being reduced. Here in Maine, we average 1 cord of wood produced per year, per acre. With an average value of $18 a cord for stumpage, it costs more to pay property taxes for a given acre, then what the land produces for wood. So, people are selling off large tracks of land.
That tax burden does not sound high ($26 an acre), until you start adding up all the acres owned. My Grandfather has a tax burden of over $15,000 a year, and my Uncle, over $30,000 a year. My next door neighbor owns 3200 acres, and he cannot sell land fast enough because he cannot pay his property taxes any longer.
But it becomes a catch22. As more people in Maine leave because of high taxes, it leaves less people to shoulder the tax burden, so the tax burden gets higher...and round and round we go.