[renewiltord]

We actually respected DNT at an ad tech company I worked at and people still gave us grief for "tracking" them. We literally just 200'd the request immediately for all DNT requests. No processing, no tracking, nothing.

Hilariously, I even opposed removing the code later because I wanted us to be a good citizen but it was practically dead code because people were still calling us evil. They could literally set their UA to play along (or use one that set it by default).

I think we always kept the code in but it only incurred cost and we got blamed anyway. I think, looking back, I should have just removed that piece of middleware since no user ever really cared. It wasn't worth it for the org to pay for code so I could have a clean conscience.

[8note]

Isn't there a response code for no change?

Saying you did something doesn't help the user know that DNT was followed

[renewiltord]

We tried 202 and 204 and both led some UAs to show broken image placeholders. But during the time we did that people assumed that we were tracking them just incompetently ("Look! They've revealed themselves!" style).

Maybe we tried some other codes but anything but 200 was unsafe to many UAs (you could 3xx but UAs would break on 304 too because the tracking pixel wasn't actually cached). Anything that led to UA breakage was verboten anyway on our side since we didn't want anyone to have a broken experience because they set DNT. That would have been bullshit.

We were dumb-enough to handle P3P headers too (which AFAIK no one really used in the end). Lots of dead code. Ugh.