Why Do some people never call back?

We all have noticed this tendency among very many people, who never call back despite saying that they'll. Why don't they call back is a question. It's a riddle. In fact, this habit of not calling back stems from the fact that the person has no value for the other person, who gave him/her a buzz. It's not just lack of etiquette, it's also sheer indifference that slices the other person deep inside. Phone etiquette is something we all must know.

It's not enough to know, how should one talk on phone and how well should one modulate his/her voice to sound presentable to the person at the other end, one should also know that calling back is an essential gesture of etiquette. I'm told, Amitabh never forgets to call back and the legendary all-rounder Sir Garfield Sobers, who still doesn't use a cellphone, himself attends to his calls and never forgets to call back if he's not there.

It's not for nothing, these people are called greats, though I don't equate Amitabh with the peerless Sir Gary in greatness. The problem with all of us is that we don't have time for others. We've become too busy to attend to others' problems and issues. While it's good in the sense that it minimises unnecessary and unwanted interactions, it also reduces all individuals to 'private islands.' We must realise that if someone phones us and we can't take his/her call, we must call back when we've time. 

At least, we mustn't promise that we'll call back. If you're not in a mood to entertain a certain person and his call, don't say, I'll call back. That directly insults the other person. But in this age of internet, SMS and eroding values, who has time for life's finer things? Perhaps I'm too old-fashioned that I still care for the nuances of life and social etiquette. Am I?