Comment by FeepingCreature

I mean. It seems you've answered your own question?

She wants to avoid her kids considering it acceptable to cross a red light. Parent violated community norms by crossing a red light. So now she has to signal that this person has violated community norms, so that her kids learn "red light crossing is bad" rather than "red light crossing is normal".

This is not a "german" thing, this is a "human" thing.