Essentially by definition.
Property value escalation either means that the actual structure becomes more valuable (something that very rarely, if ever happens), or that the ground underneath becomes more valuable.
The land becoming more valuable (up to $X) is equivalent to saying that the market price on the unimproved land is now worth $X-- this is the amount of money any landowner can expect to collect on this land, given the proper amount of improvements upon it.
Since there is no marginal cost in the unimproved land, the entire return to this land is pure Economic Rent. The LVT would tax the full Economic Rent of the land (which is essentially equivalent to an annuity on $X, for land worth $X.)
Why wouldn't the landlord pass on the LVT to tenants? Competition, essentially. Land would only be desirable to be held by people well-equipped to build (and gain the return on) the proper improvements. These landowners would have an advantage over a landowner who does not make the proper improvements, and competition would drive the market rate of rent towards the marginal cost of improvements.