An example: I went to a phone-free drink lounge with a group of people. Before the event I texted the group saying "this place takes your phone at the door" and everyone said they were cool with that and that it sounded fun.

We all knew going in that this is what we were signing up for.

It's like going to a club with a specific dress code. You go there for the atmosphere and the unique experience. And yeah everyone agreeing to not have a phone in their pocket does change how people in a group interact with each other.