I find people to be...assholes

It never ceases to amaze me, you go into a restaurant, it cam be totally packed or damned near empty and people carry on private low tone conversations. Even then, with enough people it can produce a resonance that 
causes a vibration in the air
People.usually talk quietly amongst themselves, I am not sure if this is because they are trying to be courteous to other people or they feel the conversation is private. Now, give anyone of these people a phone and all of a sudden they are talking to the world. It's as if the telephone precludes courtesy. Why do these people feel that I want to hear anything they have to say. 
The best part is...After they tell all their private business to an entire room of strangers they close the phone then in soft tones again, tell the person sitting across from them everything they just told the person on the phone. It's as if they think that person could not hear everything they just said...Hell, the dishwasher in the back room knows what they said.