We already do/did it was called Do Not Track. The companies that profit from cookie tracking had no interest in complying with it. The situation with GDPR compliance is that most websites today aren't compliant, you are meant to opt in rather than out and forcing you to choose is also breaching the legislation. The web industry is seeing how much it can get away with breaking the intent of GDPR and still forcing in as much advertising and tracking as possible. These banners shouldn't exist and certainly not with all these dark patterns.