Just Call Me

I don't know why people don't call people back. Especially when a message is left and in the message it is specifically said to call the person back. Then there is the fact of never calling back. I can understand if a person is busy that day or night but weeks go by without a return phone call is kind of rude. A simple "hey sorry, I've been busy" return call goes a long way. Then I start to wonder, does this happen to alot of people anymore? Is this a new trend? I know individuals who are notorious for not answering their phone and never calling back, which makes me wonder why they have phones. It just seems to be happening on a larger scale now, not just 1 or 2 people but pushing the majority.