Why do you think it's no longer possible? What does the size of the government have to do with tax rates of land?
If the budget is, say, 100% of the value of the land, you're stuffed? I mean, obviously you can set a tax rate as multiples of value but land almost immediately becomes worthless and all multiples of 0 are 0.
Who would pay money for an asset with zero returns at all (or indeed negative returns due to a bunch of administrative costs)
Neither does the market, btw.
At a 100% LVT the price of land is $0 (or more accurately equal to the price of the improvements on it). Above 100% LVT the price of land is negative so building any improvement immediately loses money and a whole host of other negative consequences.