The parent comment is a bit flip and sarcastic, but he's not wrong. $550k isn't even a speed bump for Twitter. SV tech companies aren't going to take EU regulatory bodies seriously unless they pass out meaningful fines.
Hopefully, Ireland’s Data Protection Commission intends this to be a "shot across the bow" hinting at more severe fines if Twitter continues to do this kind of thing. Otherwise, Twitter is unlikely to change their behavior.
I would be surprised if any US company would have had the foresight to call European authorities within 3 days of a serious issue in 2018 .. especially with whatever skeleton crews are working over Christmas.
It's been a learning curve, and things like this have been good lessons to bring us to where we are.
Hopefully, Ireland’s Data Protection Commission intends this to be a "shot across the bow" hinting at more severe fines if Twitter continues to do this kind of thing. Otherwise, Twitter is unlikely to change their behavior.