Well for one, I personally have never seen all too many White-Tailed Deer in zoos. When I have, they've always been rescued animals that are not breeding. I think the only zoos I've been to that breed WTD are roadsides. How often when wild rescues are in zoos do you actually know they're rescues? For some species it's obvious but that's just because we, as zoo nerds, know those animals will most likely be wild born rescues.
I don't know the situation with WTD in zoos in Wisconsin and surrounding states, but if you're really encountering the species this often in zoos, it might just be a regional issue.
~Thylo