my car met a deer...and my wallet's crying

Had something similar happen a couple summers back—hit a raccoon on a road trip and thought for sure it'd be collision. Nope, comprehensive. Asked the agent about it, and he said hitting animals is always comprehensive because they're "unpredictable hazards," not stationary objects or other cars. Still seems kinda arbitrary to me though...wonder what happens if you swerve to avoid the animal and hit something else instead?