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.