Crothian said:In a world of magic a low magic army that can't deal with a flying wizard is useless and thus wouldn't exist. In these worlds they have been fighting wars with magic for thousands of years. Both sides would have magic and anti magic capabilities.
QFT. Moreover, this line of reasoning covers a lot of the supposed holes in the world design: unless one assumes the PCs are unique (not a bad premise, but generally pretty far from the base D&D assumptions) they will hardly be the first to cone up with their brilliant plans. If high level PCs use S-B-T actions, chances are high value targets long ago learned to operate under the assumption of potential S-B-T attacks. Likewise, traps and magical defenses in tombs make perfect sense: the high priests and kings of old know adventuring tomb raiders use spells and such to plunder the treasures of the dead.
This is why I think it is really important for verisimilitudes' sake for the GM to decide what the general "magic level" of the setting is and stick to it, especially as it relates to the "average person" which, presumably, the PCs are at least when they begin their careers.