i bought my phone in June and in July it ended up in a foot of water for a minute or so. Face recognition and hey siri no longer work. Why is it advertised they are water resisten for 30 minutes in 4 meters of water, if they really aren't?

It is advertised they pass international IP water resistance ratings, which use those settings for testing under cintrolled laboratory conditions, not real world use.

And nothing about an IP water resistance rating guarantees water exposure cannot cause damage. It just means it is less likely to cause damage than a non-IP rated device would. But any water exposure still may cause damage, and will be circumstance dependent.

About splash, water, and dust resistance of iPhone 7 and later - Apple Support