Caller ID

Why do people with Caller ID return a call if there was no message and they don't know the person who called? About an hour ago, I made a phone call and got the wrong number. When I got the woman's voice mail and realized I'd made a mistake, I hung up. So now the woman called back and said, "Yeah, this is Marie. You called me. Who is this?" That was worth a long distance phone call? Think about it, lady - if it were important, I would have left a message.