Remember, archetypal landscape shooters like O'Sullivan shot for the sake of exposing the undeveloped land to eastern developers. The goal of the photos was: here it is, let's exploit this!
(I won't rehash the modern version of the same sentiment, where landscapes are used as backdrops for SUV ads that promise your ability to "conquer any terrain")
One shot or twenty, the real "ethical" issue in landscape photography is what is your relationship to this land as expressed in these photographs?
The camera is a dumb instrument. If you do not think about what is in your pictures, it will also record your indifference.