Iran was in the process of establishing itself as a democracy when the US, in a CIA backed coupe, crushed Iran's fledgling democracy and installed the Shah in its place. It's not that Iranians aren't capable of understanding democracy - but they understand the geopolitical realities that countries in the Middle East face with regards to Western powers. They understand that it's very difficult to establish a free and open democracy in the face of the efforts by Western governments to control all of the resource rich and militarily strategic regions of the world at the expense of the local populations.