Land is not a good, because it cannot be produced by human labor. A good is something that is created by humans using natural resources, i.e. the productive output of land infused with labor.
> what economists would refer to as "land" (unowned resources)
I have never come across this definition of land anywhere in economics. A more accurate description would be "unproduced resources". It is anything that exists in nature independent of human activity, and a distinct factor of production from capital and labor.
> You are not taxing the land, you're taxing the conversion of land into property
This is a total misunderstanding of land value tax. LVT taxes the monopolistic holding of land in order to collect rent. It does not tax any property developments or improvements (mines, cafes, farms, factories) on that land.
If a landowner expends labor to extract resources or improve the value of his land, those are improvements, which logically are untaxed. A LVT in lieu of other taxes would encourage the development of land into property, not discourage it.
> the act of identifying useful, unowned resources and claiming them for human use.
Again, it only taxes holding resources without using them -- it explicitly has zero taxation on productive economic activity such as mining, farming, or operating a business on land.
Furthermore, I contend that the act of identifying useful resources and claiming them only, is not a valuable activity, and can be taxed. It is the actual utilization of the resources to produce goods or services that adds value -- merely laying claim to land without productively utilizing it is the definition of a rentier economy.
> And when you tax something you naturally get less of it; in this case there is less incentive for people to go out and discover new resources. A 100% LVT would nullify any economic motive to expend effort locating new sources of minerals or suitable farmland (etc.) since 100% of the value of whatever you discovered would be taken by the LVT.
You're right in a very narrow sense, hypothetically there is less incentive for unproductive landowners to discover resources in their own land, lest they get taxed on something they have no intention of exploiting. In return for this disincentive, LVT aligns every other incentive for the common good. A 100% LVT and 0% sales, development, income, capital gains taxes would mean you get more of the latter: productive economic activity, because you're taxing it less.
The vast majority of land value in modern economies is well known, because it is not undiscovered mineral resource value, but the value of proximity to labor, goods and services. LA, SF, NY flats don't cost what they do because there's gold under the floorboards. The value of infrastructure, proximity to various labor, goods, and services markets is what makes up the vast majority of land value today. A LVT taxes those who hold land without adding improvements (the unearned increment), and incentivize entrepreneurship and labor (the new office building or high-rise will be entirely untaxed, nor will there be any sales or income tax on the valuable economic activity of its inhabitants).
> This form of "land value tax" is deceptively named; it should really be referred to as a tax on gross external benefits received.
I agree with you here entirely. Another name for gross external benefits received is "the unearned increment".
> Which has some obvious flaws, for example that the property owner has little control over external benefits others may unilaterally choose to create, and also that one pays extra tax on any contribution one makes to one's own community which has the effect of raising property values. (In fact, under a LVT system unilaterally contributing to the community and making it a nicer place to live might well be considered harmful since it raises everyone's taxes…)
These are not flaws. The property owner pays exactly as much in tax as is required to offset the external benefit received, therefore there is no harm done to them economically. There is no free lunch for them either (infrastructure, the cafe next door's productivity, the high quality state run school a block over). Making the area more attractive is not harmful as long as the tax does not exceed the unearned increase in land value received, which it shouldn't, by definition. Furthermore, not every improvement in a community leads to an exactly equivalent improvement in the land value, this would be mathematically impossible if you grant that services, goods, building have value apart from land.