Who are these companies?
Who are these companies?
It's a symbolic flag to respect users preferences or browser vendors are going to make ad-block standard by default just like pop-up blockers.
If ad companies ignore DNT they are digging their own graves.
It's not about protecting users. It's about heading off an arms race to help protect the ad industry.
Sending "DNT: 1" in your request header means "please do not track me". Sending "DNT: 0" means "I don't care if you track me". Sending no DNT header (every request on a browser where the header is unsupported or a browser has not received a preference from a user) means "I have not expressed a tracking preference or do not have the ability to do so".
By having a default sent either way as MS did, it violates the semantic meaning of the header, meaning that the receiving server can't distinguish between "no preference" and "don't track"/"go ahead". It's like a pair of radio buttons: selecting neither is valid, but once you've made a selection you can't get it back to an unselected state.
The common argument is that it is:
1) Advertisers won't give up tracking across the board. It's too lucrative for them.
2) Most users don't care about the setting that much.
3) Enabling it for default for the majority of users will cause present advertisers with a majority of users who they cannot track.
4) Per (1), the advertisers will then elect to ignore DNT.
5) DNT becomes a useless ignored flag and a waste of time.
Instead, if it's opt-in:
1) Most people don't bother turning it on.
2) The advertisers face pressure to comply with the ones who do.
3) People who do turn it on then enjoy the benefits.
Also, the DNT specification explicitly says that DNT should not be turned on by default, for these very reasons.
I'm struggling to find a valid food-ingredient-analogy but it would be very different from your scenario. It would have to involve Microsoft auto-scanning the ingredients without the user ever turning this feature on. Then Microsoft would have to do something with the results that hurts/disparages certain food producers. And then the food producers would stop listing ingredients in a form that Microsoft can OCR, not lie about them.
It seems to me that the harm is greater not naming names - reputation is important and if you take steps to invade user's privacy then your reputation can and should suffer for it.
[1]: http://blogs.msdn.com/b/ie/archive/2012/12/13/update-to-alle...