Servers have access to both the DNT header and the browser id. Advertisers could have argued that the DNT header sent by some browsers was not an informed decis

Servers have access to both the DNT header and the browser id. Advertisers could have argued that the DNT header sent by some browsers was not an informed decision and likely forced those browsers back to explicit opt-in/opt-out by users. But they did not. They used the first escape hatch they found to ignore the header completely, kicking the can further down the road. Of course they did, because every body knows how many people will opt-in to tracking without being bribed.