If I remember correctly, one of the reasons for it being ignored was that some browsers (rightly IMO) had the setting enabled by default.

Some places still respect the header. Medium does - you'll get the warning for embedded content.

Because rationally, tracking should be opt in, not opt out. Arguing that customers desire, by default, is shockinging disconnected from reality.

Properties should be defaulted to what is most likely user desire, I think. So for DNT this would mean “true.”

It was ignored because companies that make money from tracking also make browsers and web sites.

And now Safari removed DNT because sites were using it as a part of fingerprinting across websites.

Advertisers couldn’t care less about privacy.