There's rational fear, which is more a sort of respect I think, which seems to be what you're talking about. But with young kids there is often a sort of phobia sort of fear where they refuse to get into the water, refuse to dunk their head under the water, or refuse to let go of the side of the pool even when somebody is holding them. We spent a lot of time trying to coax kids through this sort of fear.

If their fear kept them away from water forever, it would serve them well enough I guess... the problem is, if you don't get kids swimming young then when they get older they will probably push through the fear on their own to fit in during social situation rather than in an instructional context where somebody is prepared to help them through the learning process safely. That's how you get teenagers jumping into pools during pool parties and immediately starting to drown.