I know it is hard for you to grasp this Don, but one third of the US electorate doesn't vote in primaries or caucus, because they are not members of either political party.
We still vote and participate in our democracy, we just do it in a very different way than you do.
So why are you so harshly judgmental about that?
Exercising our democratic freedoms through voting, petitioning the government, organizing protest movements to work for change, fighting through the courts--all of these are ways Americans participate.