Why were they from the states?

I am just wondering why they decided to make this family American, even though the actors were obviously not? I know no one here knows for sure but would love some speculation from anyone, especially Swedish people. Is the family meant to seem so totally over-the-top tacky/American/80s or were they seen as average for the time? Did they speak Swedish with American accents? Since everyone in the film spoke the same language, Allen, the mailman and the family, was there a difference in accents? Just curious.