If we eliminated all other methods of taxation, what do you think would happen to rents? Would they increase, decrease, or stay the same? How do you think this affects the amount collected through a Land Value Tax?
The value of the land is a function of the amount of money one could make off the land, which is a function of the overall economy. A coffee shop next to lots of office buildings can sell lots of overpriced coffee which affects the value of the land it occupies. If the economy gets bad the coffee shop will likely not make as much money, so the taxes off the land will be less as well.