Frog expanded beautifully on my point about wizards in the BC series. They are being actively hunted by everyone out there, from enemy soldiers, to supernatural creatures, other wizards and the 'heavy' mages (Taken, Shadowmasters, and even the Dominator reaches out to the minds of the Taken from his entombment-if a lower level mage caught his attention, I imagine he could fry them or enthrall them with exceptional ease [re: the Lady and Bomanz]).
Wizard mortality has to be extremely high, and the risks the higher you get keep escalating as well. The best chance a wizard has is to lay low, blending in with the surroundings and keep a spell handy when it is time to bolt. The points in the books where the Company wizards take the upper hand are rare, and after they do pull off a spell, they 'fade' as soon as possible.
hellbender