I find it is as common as technicians with the same attitude - I only work on this brand of vehicles.
I also think part of it comes from a level of comfort with their ability to do the job correctly. For instance, I may be guru on GM claims, but do I feel comfortable hacking through a Mazda claim? If I know enough about submitting claims then I probably realize what could happen if I do it wrong. In many cases I just think that the administrator doesn't want to learn another line because they want to be an expert walking in the door.
The problem is what you relate in your question. Let's say I am a Ford/Kia store and my warranty administrator leaves for greener pastures. I could probably look around and scrounge dig up someone to do Ford, but what if they refuse or struggle to learn Kia. That continues to be a problem. That might have been possible for a WA to get away with a few years ago when the domestics were the biggest hunk of the warranty business. Here in NJ a Ford/Kia store or Chevrolet/Hyundai is probably 50/50 in warranty work between the franchises. I tell new warranty administrators to learn as many franchises as possible and not be afraid of any of them.
Personally, Id be more afraid to flip between R&R and ADP than between two factories, and it is funny that few are resistant to learning a new computer system.
------------------
** Rob, Editor WD&S **Help is only a message post away!
robc@dealersedge.com