Tbf, if you are an American (both North & South) minus Canada & saying that Avatar cultural impact isn't much or whatever, you are likely not that wrong.
The performance in Americas is of Tier B blockbuster.
But overseas + Canada, now here Avatar is a Tier A stuff along with Avengers. Here that would be complete false.
Unfortunately media and internet discourse on Internet is America heavy, and Americans are pretty ignorant about rest. So we are in this position.
Not really a huge sample, but this is the result of TWITTER poll I had earlier last year