I'm used to the value of the land vs. the structure being listed separately on a property tax bill. The value that is attributable to the community is the valu

I'm used to the value of the land vs. the structure being listed separately on a property tax bill. The value that is attributable to the community is the value of the land before building. Obviously that's far higher in the middle of NYC or SF or something. So I'm not sure what you are saying about low density housing. There is/was a political movement to finance everything with a tax on the unimproved value of land. The advantage is that with almost everything you can tax, you get less of it, which is usually bad, and besides leads to avoidance and lower revenue. But unimproved land cannot be "discouraged" by taxes, and owners cannot pass the taxes on - their incentive is then to not leave it vacant, which is a very good thing in a dense city.