But the problem is most of us are not trained to negotiate. Most of us find negotiating uncomfortable, since we don't do any negotiating at all. We just buy what we like, at the price stated on the sticker.

Car buying is whole different process than any kind of buying and selling. You (an amateur) go head-to-head in a small room with a practiced professional who is constantly pressuring you to buy a car - right now. There is no one there to make sure you're not being ripped off. In fact, most people are there to tell you what a good deal you're getting and you should hurry up and sign - but just the opposite is the truth. Most people find negotiating for a car so distasteful that they just hurry up and sign on the dotted line and end up paying a lot more than they should - just to get the whole thing over with.