I suppose for a 3 year old the whole universe is about them isnt it ??? LOL. The whole world revolves around them, when they want a drink, they want it now, when they want a book read to them, they want it now. I suppose as they get older the whole concept of 'waiting your turn' is all new to them. Theyve never had to wait before....(as a baby...) you were there all the time, when they screamed, cried, someone came....Their little minds must be thinking 'why should i have to wait, i want it now?'..... To them the whole world is your home, is you, is her dad....nothing else matters. I dunno, but i have experienced this with my now 4 year old. She was like your daughter....and even now, when im on the phone, will ask me (politely) to help her unscrew the lid of her glue , with absolutely no care in the world that im on the phone....I must admit she has gotton better with time. I simply explain to her that mummy is doing something and as soon as i finish i will help you with whatever.....

Personally i just think she is doing whatever normal 3 year old does....thats my opinion anyway.
Goodluck....