I think when you're giving or going to be giving someone a lift and the opportunity to do any of the above comes up, what it comes down to as much as anything else is whether you'd be happy if they were giving you a lift and doing what you're considering doing. If the answer is no, then clearly you shouldn't do it from an ethical point of view, whether or not it's within the bounds of the law.
IMO it's a bit different if you're the only one in the car. It perhaps shouldn't be, as there're still other drivers on the road, of course, but somehow you're less responsible for them.. I suppose they can at least try to avoid you if you do something silly, whereas the person you're giving a lift to would just be screwed. Plus, with texting/phoning, there'll be times when you can do that without being a greater risk to other road users - e.g. empty road - whereas there'll never be a time (other than stationary traffic) when you'll not be a greater risk to your passenger.
But a lot of it does depend on the road situation. For example, driving through town I wouldn't be entirely comfortable with having a (handsfree) phone call even just by myself, due to the nature of town driving needing lots of attention. But on a motorway, I'd be perfectly happy to have a phone call even with passengers, aside from it being a bit rude
and I wouldn't mind the driver doing likewise, if I were being driven, just as long as it's a safe road with no surprises.
/waffle
