Here are my rules for using the phone in the car: I don't.
If someone calls, I let it ring and go to voicemail. If I'm expecting something that may be urgent, I will pull over as soon as practical and check it. Otherwise, I will wait until I get to my destination. Really, the vast majority of the time it's something that can wait. In fact, I've never had a situation in which something critical depended on me answering right then. I tend to try to avoid getting into such situations.
How do I give an ETA? I do it before I leave. Sure, traffic might be a bit bad, and slow me down a bit, but usually that can be reasonably well predicted (based on rush hour, weekends that lots of people are travelling, etc). If my prediction is wrong? Well, life goes on. People got on just fine before the invention of cell phones. If it's a multi-hour journey and I will be substantially delayed, again, I pull off to make the call; usually there's a rest stop somewhere reasonably accessible.
Do you really think that your life is so important that you must put other people's lives at risk just to give an ETA of when you'll get there, and you can't be bothered to just plan a little in advance?
Of course, most of the time when I'm in the car, it's with someone else. I generally avoid single-occupant trips. I commute via public transit (where I can talk on the phone all I want safely, though generally limit it to be polite to other passengers) or bicycle (where again, I pull off if I need to make a call). My trips in the car are generally only for longer trips, which I share with someone else, and I can ask them to call or answer for me if I need.
If you find traffic predictable, you probably don't live in Los Angeles. As for lives at risk - my decision to commute to a client is orders of magnitude more dangerous to people around me than the momentary distraction of letting my wife know whether I'll be able to provide child care. I'm personally OK with doing that, so long as I take steps to minimize the risk to myself and others.
It sounds like your situation and/or value system is different.
If someone calls, I let it ring and go to voicemail. If I'm expecting something that may be urgent, I will pull over as soon as practical and check it. Otherwise, I will wait until I get to my destination. Really, the vast majority of the time it's something that can wait. In fact, I've never had a situation in which something critical depended on me answering right then. I tend to try to avoid getting into such situations.
How do I give an ETA? I do it before I leave. Sure, traffic might be a bit bad, and slow me down a bit, but usually that can be reasonably well predicted (based on rush hour, weekends that lots of people are travelling, etc). If my prediction is wrong? Well, life goes on. People got on just fine before the invention of cell phones. If it's a multi-hour journey and I will be substantially delayed, again, I pull off to make the call; usually there's a rest stop somewhere reasonably accessible.
Do you really think that your life is so important that you must put other people's lives at risk just to give an ETA of when you'll get there, and you can't be bothered to just plan a little in advance?
Of course, most of the time when I'm in the car, it's with someone else. I generally avoid single-occupant trips. I commute via public transit (where I can talk on the phone all I want safely, though generally limit it to be polite to other passengers) or bicycle (where again, I pull off if I need to make a call). My trips in the car are generally only for longer trips, which I share with someone else, and I can ask them to call or answer for me if I need.