"It's a fine strategy, they know it's wrong but know that unless someone takes them to court and pays the expense of doing it they can carry on."
In Europe, the loser pays the legal costs of the winner in civil proceedings.
"They just need to decide to change their mind before any major legal expenses are due."
However, breaking the GDPR is NOT a civil dispute, but breaking the law. What Mr Ryan did was informing the Irish Data Protection Commissioner that IAB was breaking the GDPR. Which means that even if they change their policies, they were still breaking the law and could be punished.