Why is it so hard to say goodbye?

I'm talking about phone conversations, here. For some reason we need to repeat the word, 'goodbye', and say it in at least 17 different ways before we can hang up the phone. And even as we pull the receiver further away from our mouths to hang up we are still saying goodbye. 'Ok, bye then, see you later, have a good one, see you round, let's block the phone lines for no reason, take care, so long.' Actually, no one really says 'so long' anymore. I think it means, 'SO this is a LONG phonecall. Hang up already.'
Interestingly, I find that if I yell goodbye in the voice of an evil Grover, people on the other line are compelled to say goodbye in a similar silly way. Try it sometime.
If I am person to person, I don't say goodbye 17 times as they walk away from me. In fact, I don't even speak, a wave is fine or even, 'Get the &*%$ away from me', and we're done. Nothin' more to see here, people, the show is over.
We also have the lead up to goodbyes. 'Ok, I'd better let you go', a polite way of saying, 'Totally bored right now'. Then there's, 'Well, I'm on the mobile so I'd better go,' a polite way of saying, 'I'm a tight arse and you are boring.' Let's not forget, 'I've just got someone on the other line,' another way of saying, 'I'm trying to get rid of you by pretending to be popular.' I always find that, 'Yikes, dude! My colostomy bag just burst' works. People don't want to keep talking after that, or eating for that matter.