In a small country town everyone knows everyone and you do not get away with bad behaviour via annonimity. The shame metered out by the community usually keeps everyone pretty much in-check most of the time.
I large cities we all revel in the annonimity, (like many do here). In the city we can get away with being many things we cannot get away within smaller communities. Much the same as it used to be when blokes didn't swear around women. "Ladies" didn't like to hear coarse language and didn't like those that used it, so blokes refrained when in their presence, "ducks on the pond" anyone.
The corrorally is true with racism, if we cared how we were thought of, by those the racism is directed towards, we would not do it. If the adolescent in the Goodes matter had a BFF of aboriginal herritage before the event, she might be struggling to maintain that friendship now. This sort of close-coupled consequence is what makes people think about their actions.
Now in a large annonomous city the only way to make it generally known how people behave is to use the media. Be it mainstream or social, if people realise they can be held to account they will act differently in public.
This may not change how they think, but in a civilised and tollerant society it is not what you think but how you act that maintains the civility.
After all if Adam were not civilised he could have jumped the fence and slapper her face for insulting him. He acted in a ideal way for all concerned. As adults we should not let the young go "unguided" when they perpetuate the errors of their parents and peers.
Just think how many lives could have been saved across the world if children did not inherit and act upon predjudice.