You don't see polio cause everyone in the first world's vaccinated against polio. I've seen probably rabid animals myself. If your animal's outside unsupervised for any amount of time, it absolutely should have a rabies vaccine. It can't tell you what happened to it when it comes back scratched and bloody. Did it tangle with a rabid raccoon, get in a fight with a neighborhood dog, or get tangled in a jumble of barbedwire? Are you sure? You willing to risk your families health on that decision?