Could be because the provided setup us so uncomfortable.They use hand mic's. Just from the several times I have jumpseated on United, the one thing they seem to do different than any other airline I have jumpseated on, is remove their headsets, turn the speaker up, and use the hand held mic's when they reach cruise. Nothing wrong with that technique, just seems to be a United thing. I've only been in the cockpit 7 or 8 times on United, but that was the one difference I noticed.