It's not even good neo-classical economics. A land tax can't have any disincentive effects on mobile capital or labor. Could actually relieve taxes on those things. Or it could finance public services which stimulate private sector development. The only reason to oppose it is if you own land.
It's also a real thing in the U.S., albeit not in wide use. Pittsburgh, Pa. and other burgs in Pennsylvania are experimenting with it. It's been written about by Wallace Oates and Robert Schwab in the National Tax Journal.
The idea of such a tax replacing everything else as a 'single tax,' especially in the U.S., is nonsense. It is a logical device for local governments, who have the most reason to be cautious about taxes on mobile capital or labor.
There is a kind of cult which also promotes the tax, so one must take care to separate chaff from wheat in examining the record.
MBS