The base of the land value tax is the value of the land though. If the land is in the middle of a high population density area then the land is worth more and it generates more tax revenue.

The difference between this and property tax is that if you have a 12 story building on one piece of land and a 2 story building on the adjacent one, otherwise identical piece of land, they both pay the same tax, giving the second property owner more incentive to build.