But now consider idle land that's being held speculatively. The landowner expected to sell it at a profit in the future, but now those profits are impacted by the LVT. To maintain their profits they would need to find tenants for the land in order to pay the LVT. (Or settle with less profit! :P)
Can you expand on this point please? Why would it be necessary to earn rent from idle land in order to pay the LVT? Wouldn't unused land have a low value under a LVT system, much like it does now?
I think you're right that introducing LVT could lower the already low values of unused land. Perhaps its introduction would mean a glut of sales of land: fire sale! (Win-win again, according to my armchair-economics analysis. :P)
Not necessarily, although that is certainly how it works in many residential situations.
The general idea is removing the marginal disincentive for high-value _use_ of the land. Property taxes mean for every dollar you spend making something more awesome, you get taxed more. Instead, we should encourage awesomeness on the margin, and discourage people who use land that could be awesome in the least awesome ways.
That's only a win-win if you don't value nature very highly. LVT sounds like it would force even faster destruction of invaluable biospheres like rainforests.
We already do this a little bit in some states of the US with homestead taxing
If we assume that all rents are at their market maximum (e.g. landlords are making minimal but still positive profit) then adding a tax to all will simply raise that equilibrium.