My take.
The Euro "cookie popups" were a stage in the normalization of deviance to the popups that harass people everywhere they go on the web.
The Euro popups were mandated in some countries because the Euro zone didn't like it that Google and Facebook dominated the web. Thus they had to pass laws that would ensure they would never have Euro zone competitors.
Any resistance that devs, designers, and others who care about UX was destroyed by "it's required by law". By the time everybody started chasing away their customers with popups, it was too late.
