This goes a little off-topic, but isn't it still allowed to take pictures of people in public events without their agreement? I don't think GDPR affects that. Or am I understanding something wrong from what you were trying to say?
It's allowed to take pics but if you were to use them for something outside the private sphere of your home you're obliged to ask them. Nobody does this of course.
It would be friendly of the photographers to ask for permission, when the photo isn't about a group of people in general hanging around but include people more closely, or doing something questionable, but I don't think it is obligatory. Also the one publishing the photos of public event would usually delete the photos, if a parent told they don't want their children's faces published like that. But afaik, if you attend a public event, you must also accept that there might be media reporting too.
So why does google have to blur everyone on streetview without them asking?
It is sometimes possible to know the photographer of pics on facebook but often not. I never place a pic of someone else on facebook.
I think it's an neverending discussion.
Personally i couldn't care less that i'm on a picture for everyone to see but not my kids, they cannot defend themselves.
Publishing photos of a burglar is different, because that situation isn't (probably) as "public", and then there's that "innocent until proven guilty" thing – yeah, even when it's obvious that the person is doing something illegal, it isn't up to the person publishing the photo online (like a shop owner) to decide.
It is done over here because the system in Belgium is as rotten as can be. Too much to mention:-)