Hmmm, yes, I think you're right. I'm wondering what degree of realism do people expect from maps of this type.
I mean, many fantasy maps are realized for fiction. Now let's take the example of a fantasy novel.
I don't think the reader cares how long or wide is that river, he cares only if the protagonist is strong enough to cross the river despite its width. And this puts all in perspective, of course.
On the other hand, if you buy a book and see a map of the world it's set in, you want to see a nice image. Perhaps you're not going to study the geography of the place, and you will use the map just as reference when your direction sense gets lost, but what you want as a reader/buyer is something cool to see. So the artistic map, cool and not necessary precise.
But, as a cartographer, what should one try to achieve?