It is up to the websites to do that, and to the users to boycott those websites showing cookie popups.
The regulatory body could clarify that a DO NOT TRACK header should be interpreted as a "functional/necessary cookies only" request, so sites may not interrupt visitors with a popup modal/banner if it's set.
alt Hacker News
The regulatory body could clarify that a DO NOT TRACK header should be interpreted as a "functional/necessary cookies only" request, so sites may not interrupt visitors with a popup modal/banner if it's set.