Because it is so huge, you can't really get a close up of OM - you must be far away to take it all in, and at those distances it loses all sense of scale, especially because there's nothing much around to compare it to. It's sort of like trying to take a photo of the Empire State Building from one block away - all you'll get in the frame is the lower floors, or if you tilt the camera upward to get the top in the shot, most of the lower section will be out of the picture. You need to get halfway across the city to get the entire building in frame, and you'll get a sense of size because there's lots of things around to compare it to and because it is much taller than it is wide. OM is really big around - pretty much the size of Arizona - so it just doesn't look that tall compared to how big it is around.

That said, there are many great shots that give some idea of scale (just google "close up of picture of Olympic Mons), and you'll also see side by side comparisons of Everest and OM.