Missing the point
Whether Facebook, Google, Apple et al ignore Do No Track in request headers is utterly irrelavent.
When I select that option in any browser (as I always do) I am stating to the advertising world that I EXPRESSLY do not give my permission to have my behavior tracked - err, GDPR people!
I suspect the recent spate of stories about this is more of an indication how the advertisers are trying to remove my option of telling them to 'do one' that it is about any concern for my wellbeing!