You never heard of Iron Man and Green Lantern? I've probably read five comics in my life and I heard of both.
Did you know Tintin and Asterix though?
Asterix no, but I read Tintin as a kid. Although American culture is generally more available in Europe than French culture is in America.
And I think the mention of "built in audience" has to do with a built in audience in the largest movie market, which still remains the United States (even if it is diminishing).