Our Loonballs Vs. Their Loonballs

Why is it that whenever people in America shoot up schools or post offices, or spout neo-Nazism or white supremacist rhetoric, or concoct hateful videos about other people's religions to senselessly provoke anger and retribution, we expect reasonable observers abroad to recognize that these are just our extreme fringe, not at all representative of most Americans...yet when we see furious "Death-to-America" Muslims on TV, we assume we're seeing the whole Muslim world rearing up?

[By the way, my understanding is that, both in Farsi and in Arabic, the "death to..." construction really functions more as a "down with...." statement. Though it's certainly used, as well, by some loonies with death on their minds.]