Why don't auto dealers offer anywhere near Blue Book prices on used cars?

I looked up my current car on Kelly Blue Book online. According to that, my it is worth around $8000. However, I can't find any dealer who offered me more than $1000 for it. I always tell them "You have my phone number. When you come to your senses, give me a call." but I never hear back from them. It seems dealerships aren't as desperate as the media purports.