You know, I don't agree that it doesn't "accurately reflect user intent." I've had at least a couple dozen non-techy average users tell me in the past few years how creepy it is when ads for a certain thing follow you all over the net. I've yet to hear one positive comment about it.
But that's okay. Nobody uses Yahoo anyway, so they're not going to notice. :)
It's very simple. When you install IE10, it should force you to respond to a screen explaining Do Not Track and asking if you'd prefer to be tracked. Then it would reflect user intent. But no one's asking for this because they know the only "Yes, please track me" votes they'd get would be from people who misread the form. ;)