OK, so there are classes of activity that are fairly inelastic, but not as inelastic as those requiring use of land. Fair enough. But why would the cost of air travel not increase in response to UBI? It's not inelastic, but modest increases don't appear to reduce demand much at all. Or eggs (again, not inelastic, but not very elastic either)?
The housing:land demand ratio is also not fixed, due to multi-level dwellings (hence, for example, Singapore or Hong Kong), or increased density (e.g. ADUs or smaller lots).
I just don't see why you see UBI only affecting owners of a nearly-inelastic resource (land) rather than everything else too (even if to a lesser degree) ?