Depends on the phone, but some of them, the audio is horrible through the regular speaker for calls, but better via the bigger one. Just not necessarily enough better for everyone.

Mind you, most of the people that do that are just twits, but hard of hearing people might need to use the phone that way to be able to communicate effectively, regardless of phone quality.

I'm the kind of person who takes phone calls on speaker almost exclusively (unless I have headphones), but never in public what the actual fuck. I hate those people too.

I think they see it on tv shows or social media influencers, where it allows both sides of a conversation to be heard by the audience. And if TV or Kim Kardashian does it, it must be cool, right?

Gotta keep those waves away from their delicate grey matter.

That or their phone has shitty palm detection and will unwittingly treat their face as a touch if they hold it too close.

They are in the same group of people that insist on playing music on their tinny device or little boom box while walking down the street.