What force could possibly make desert drainage systems significantly different from tropical ones? Chemical erosion? Chemical erosion occurs so slowly as to remove insufficient material to greatly affect the landscape. Wind erosion? Sure there are deflation pans, but these are small scale features. Dunes may fill in stream channels, but they seldom define or restrict basin topography.

My point here is that it is rain and consequent stream flow, however infrequent it may be in the desert, that accomplishes almost all of the removal of material both there and in the tropics. While desert basins doubtlessly evolve more slowly, the ultimate land forms achieved over geologic time differ little because the removal processes are largely identical.

I did not disagree with Stepinski and Coradetti's conclusion that many drainage basins are fundamentally different on Mars. I disagree with their conclusion that this difference is evidence of erosion under desert conditions, for the reasons stated above.

I don't have my book on fluvial geomorphology right now, but I'll consult that - and post some pictoral evidence - since you're so particular, Nick.