Seeing this from the inside - I believe that large/reputable advertisers have no problem[1] with e.g. GDPR being opt-in, because it's a law that levels the play

Seeing this from the inside - I believe that large/reputable advertisers have no problem[1] with e.g. GDPR being opt-in, because it's a law that levels the playing field. With DNT, the question was "who blinks first" - it was all too easy for some players to take the stand that "it's not user intention thus it's irrelevant" in order to force everyone else to do the same. MS abused the industry-defined standard and twisted it into something that it was not meant to be, so then it became ignored. [1] Ok, not "have no problem", it's a lot of technical work that is not "feature" and they need to pay for. But again, rules are the same for everyone, and "full GDPR support" can be sold as a feature, so they're largely fine with it. There's also slightly inconsistent interpretation of the law, depending on company. That's also to be expected, some niche players will push the boundaries of the law hoping to get market share, while the larger ones/that have more to lose will remain somewhat conservative and just tell their clients "our interpretation is correct, if you want to go with the niche players suit yourselves, your risk". In time, as courts set legal precedents for the interpretation, this will smooth out.