Probably because it's water resistant not water proof. You can't put it 50m under water for a few days and then complain it's damaged. I guess if they are saying it's water resistant they have tested pretty extensively and can guarantee that under the conditions they say it will not get damaged. Not great that the customer has to place their trust in the company regarding that though.
That's precisely why it's spec ip67. It allows them to have their phone independently verified while still leaving the customer on the hook for damage.
Yes, it's unfortunate that if its damages under 50m it's your word versus their word.
