But does GDPR really allow this business model at all? A website cannot as per GDPR say "accept tracking or we refuse service", if tracking is not necessary to provide the service. Can they say "pay or accept tracking or we refuse service"?
That's exactly what The Washington Post does. They have a free option where "You consent to the use of cookies and tracking by us and third parties to provide you with personalized ads" and a "Premium EU Ad-Free Subscription" with "No on-site advertising or third-party ad tracking".