While what you say is all well and good and in a perfect world it might work that way. However, those that track and ignore the "Do not track" are probably missing the "ethic's gene".
Go back a bit, to when anyplace you bought something from automatically added you to their mailing list and promptly sold it to 3-rd party folks in order to "enhance your internet experience" with spam. Some laws were passed and those things had to be "opt in" instead of "opt out" (if the "out" option was even available. So.. they marketing types promptly complied and added check boxes so you could opt-in for spam. A short time later, the boxes were "pre-checked" because they just knew you were looking forward to a inbox full of their (and their 3-rd party buddies') spam. On some sites, those check boxes are well buried.
The point is... pass some laws and advertisers, etc. will find a work around. After all they'll tell you, most people want advertising. The rational I heard one time was "the Super Bowl" experience. One helluva lot of folks watch that game here in the US just for the ads. The game is irrelevant to them.
This just isn't about ads, this about privacy. I'm sure Google ignores the "do not track" and can willingly target (in a carpet bomb sense) you with a zillion ads.
Biting the hand that feeds IT
