if an IPhone is waterproof why is water damage not covered?

Hi. I think maybe the premise of the question is flawed and that answers the rest, at least as a practical matter. SO, the deal is that although the iPhone X does have a degree of water resistance, but is not waterproof. Apple strongly recommends against submerging the phone for even a moment. Or even using it near large amounts of moisture. This all is explained much better here: About splash, water, and dust resistance of iPhone 7 and later - Apple Support

Hope this helps.

-- JDee

The iPhone 10 is not waterproof. No iPhone is waterproof.

They are water resistant. There is a huge difference.

This may shed a little bit of light on how water resistance works and what the various rating mean:

Linked document --> Understanding Water Resistance

Water resistance does not equate to water proof. All it means is your device has a better chance of surviving water exposure than a non-water resistant device would have. But the IP67 or IP68 rating is not any sort of guarantee that exposure to water won’t damage a device.

All smart phone makers selling IP rated water resistance devices have warranties whose terms state that evidence of water damage voids the warranty. None of them cover damage from exposure to water.