I completely agree with your type of thinking. I've always thought the negotiation game ($9500 + $0 != $9000 + $500), while sensible from a psychological perspective, is downright silly. I'd probably act the same as rokhayakebe. Sure, it isn't a negotiation, but perhaps I don't need to negotiate. If I've got a price and I'm settled on it, we may as well get down to business. After all, my time is worth something as well, and six-hour battles at car dealerships sound like a waste of it to me.

It shows good faith. It shows your willingness to negotiate.

You can go through life upset that the world doesn't work the way it "should" - you can even refuse to participate like the original poster. But you will generally have a worse outcome, so is it worth it? Why not play along, just a little?

Same thing goes for: dressing up (why should it matter if I'm in a suit?), sending thank yous (why should it matter if I already said thank you?), and just about any other social grace.