I think part of the problem is people get bored whilst driving and want to 'chat'. I hear people doing the equivalent on trains, boring monotone conversations that aren't exactly business or social critical; but do 'pass the time'. It's just the modern way. People must engage' with others at all...
I once saw a man with a plastic cup to his ear with a very long piece of string trailing out the window. I nearly had to put my beer down as I overtook I was so astonished.