Listening

I'm in a fairly bellicose mood this morning so I thought I get a few rants out. Let me give a snippet of a recent phone conversation:
Phone rings
I pick up the phone and say "Shamsuls phone, Ben speaking, How can I help you?"
voice "Is this Shamsul?"

This phonecall is completely typical when I answer the phone for someone else. Now I accept that perhaps I am not always the most clear speaking person, so after it happened a few times I made a concious effort to enunciate and yet still the problem persisted. Then I realised that either the person calling was either unable to think fast enough to deal with the fact that someone else was answering the phone rather then the person they intended on speaking with and they needed the gap in the conversation by getting me to repeat information that they already knew OR that they just didn't listen. Given that its really not THAT challenging to adapt to someone else answering the phone I assume its people not listening. This I must admit I found a little bizare, that was until I went into the local sandwich shop.
Sandwich person "Hi sir, what would you like?"
Ben "Could I have a ham, cheese, and tomato sandwitch please"
Sandwich person "Would you like white bread sir?"
Ben "Yes, thats fine"
Sandwich person "Would you like butter on that sir?"
Ben "Yes"
Sandwich person "What would you like on that sir?"
Ben "Ham, cheese and tomato please"
Sandwich person "Salt and pepper sir?"
Ben "no thanks"
Sandwich person "With crusts sir"
Ben " yes please"
Sandwich person "How would you like that cut sir?"

Now if you examine the above conversation you will notice that although they actually ASKED me at the start of the exchange what I wanted, they didn't actually listen to my reply and consequently I had to tell them again. I have noticed that it seems to be the norm in our society to ask questions but not listen to the answer. Why has this come about? Of course another amusing side note is that even when I go back into the same sandwitch shop and ask for "a ham, cheese and tomato sandwitch on white bread with butter and no salt and pepper" I not only get a strange look but I get asked the same questions anyway.