As others have said, it's not because of a technical reason but instead because companies don't really want to comply with privacy laws. We already have tried t

As others have said, it's not because of a technical reason but instead because companies don't really want to comply with privacy laws. We already have tried this twice: P3P (https://en.wikipedia.org/wiki/P3P https://en.wikipedia.org/wiki/P3P) and DNT (https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/DNT https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/DN...), and it seems they are trying again with GPC (https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-GPC https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Se...). The important point is that this assumes that websites will cooperate, but knowing that advertising companies are actively clogging up EU countries with long-stretching lawsuits just so that they can stretch their time I foresee that GPC will be a failure (like DNT and P3P).