I am often the driver for friends and family whenever we travel, whether short or long distances. This is mostly due to the fact that I have the best track record, reflexes, judgement, etc. on the road and am generally happy to do it. I am not against passengers making/answering phone calls while I am driving, but I do not like it when they have extended conversations while I am driving. It is annoying to me because I have to turn off the radio, halt my conversations with other passengers, and listen to one side of a conversation, which is frustratingly boring - especially if it goes on for more than 30 minutes.
In the US at least, the etiquette for behavior when other people are on the phone nearby is to be quiet and let them converse without interruption. It's also common etiquette to step out of a room if you have to talk on the phone, but that is not possible in the car for obvious reasons. Correct me if I'm wrong, but I don't believe there is any kind of well known rule for taking phone calls in the car.
Whenever I am in a situation like this, I feel stuck. I have tried asking them to please wrap up the conversation, but I feel petty for doing so and am usually met with a confused look. I've also tried asking them to keep it short before the answer the phone, but either they get wrapped up in their conversation and ignore me, or they act like I'm kind of unreasonable tyrant and say on the phone, "Sorry, BlackThorn doesn't want me to talk on the phone, so he is making me keep this short."
As the driver, I have nothing else to do in these situations, so I feel like it is reasonable to expect that phone conversations are kept short. Other passengers have the option of playing on their phones, reading a book, looking out the window (at the sights, not the road), but I am held hostage to half of the conversation whenever someone is on the phone. How can I get my passengers to see things my way, and keep their phone calls short?
To clarify, this behavior is both rude and distracting. Listening to half a conversation, as @DaveG pointed out, is distracting because your brain tries to fill in the other half of the conversation. It is also annoying, which leads to more distracted driving as I start to focus on how much I wish the passenger would hang up the phone. I'm happy to converse with them to pass the time, listen to them converse with each other, listen to the radio, or drive in silence.