Technology, culture and behavior seem to evolve together. Years ago, we started to see people walking through airports talking on cellphones with headsets. In order not to seem like wierdos talking to themselves, these folks would routinely hold the headset microphone to their mouths, so you could clearly see that they were on the phone.
Then people dropped their hands from their headsets, assuming you'd know they were on the phone because of the cord dangling from their ear. After a while, the introduction of the bluetooth headset took away that cord, but by then nobody was self-conscious anymore, and it became commonplace to see people walking through airline terminals talking without shame to an unseen companion.
But now, at least for men, social norms have relaxed to a new level. Many times in the past year I've walked into an airport men's room and seen a lone man standing at a bank of urinals, actively engaged in a hands-free conversation with someone hundreds of miles away, presumably with a hidden bluetooth headset in his ear. These people inevitably speak in extra loud voices, as people speaking on cell phones in public often do. So, it's hard not to hear about the latest deal they're trying to close, or the new investment idea they're discussing.
I guess the call of the greenback makes it difficult to wait two minutes to make the call. After all, cash is king. But, I personally refuse to take part in this latest cultural development. And, I'll hang up on anyone who calls me if I hear the sounds of the airport bathroom in the background.