Who is to say we don't? I think it all depends on the situation; as a child, his only recourse to protest current conditions is to behave as he is, but as adults, more is expected and required. If we lived in such a society, I truly believe there are those among us who would rise to the occasion.
I know we've all seen the movies where America is invaded and/or overrun and how small pockets of citizens fight back- I don't believe that's just Hollywood. Our nation was built on fighting off oppressors, against greater odds, better armaments, staunch tradition- and we were still there then when the smoke settled, and I fully believe we would now if the situation called for it.
I would not necessarily disagree if you posited that a large number of our fellow citizens would simply sit and do nothing- but such has always been the way of societies back to antiquity.