Actually the Mobile Phone Syndrome you describe is quite easily explained in my experience. I am a happy
mobile phone user myself, as are
most of the UK population. (fact).
When I receive a call, I almost never tell people where I am voluntarily. The thing is, they always ask. This seems to be due to the fact that the background noise, coupled with the exquisitely sensitive microphone on my and many other phones, makes it sound like I am always in a war-zone or school playground. This also means I don't need to shout into my phone. Just because Dom Joly does a parody of it, doesn't mean everyone does it, especially in quiet locations.
When someone phones me therefore, they usually ask "Where are you?" and so I answer: "walking down the street", "in the pub", "on the train" or whichever noisy place I happen to be.
I'm sorry if other people having private conversations pisses you off, but you shouldn't be listening anyway. Not everyone shouts on the phone, so why is talking on the phone more obnoxious than talking to someone else?