My dog (Aussie) is more than happy to catch a frisbee (backflipping along the way if need be), but still refuses to bring back a ball. I think simple retrieval can be too boring for such breeds, even with high value treats it's much more exciting for her to dash around the dog park herding the other dogs and leading parades than to just bring a ball back and forth.

I do see some collies who do simple retrieval at the park, but it requires their owners to be strict about the dog not playing with any other dogs and coming back immediately. Not a way I want to raise my pup.