It's bad enough on trains. I have no idea why people scream into cells, or why they have no concept that what should be their private business is being heard by everyone.
A few years ago, a woman behind me on the Metroliner to New York was getting some work done on her beach house, making appointments on her cell phone. By the end of half an hour, I knew where her house was, where she kept the keys to it, what days she would and would not be there, and two of her credit card numbers. I could have taken over her whole life and she would never have been able to figure out how her identity - and a lot of her belongings - got stolen.
I know what you mean. I used to ride a commuter train every day.