Democracy is not a precondition of economic growth and development. In fact, sometimes it may be a hindrance. For example, China, a totalitarian state, has been much more successful at promoting economic growth than India, a democracy. Historical examples of economic success without democracy include Nazi Germany and Fascist Italy, two countries that managed to rapidly spring their countries out of the depression while most democracies continued to suffer for another decade. Thus democracy is not a prerequisite of economic development.
Yes, these other types of systems can for sure have economic growth and become a lot more wealthier, all they have to do is have some very smart people in their government, that know what types of programs will help out, and which types will make things a lot worse.
Yes, non-democratic systems can promote economic growth and development, if they have strong laws that allow for private property and individual choice. It does not matter how people have good laws put in place, as long as the laws allow them to play fairly and keep the money that they earn. It is the laws, not the way they are put in place.
There is only one form of non-democratic government that can promote economic growth and development, and that is an aristocracy. Sure, this idea is flawed too, and can be corrupted. But this is a form of government where only the best and brightest get to be leaders, and have to go through rigors to get there.
Non-democratic systems can promote economic growth. Just as a democratic system promotes economic growth, so too can a non-democratic system promote economic growth. In China, which is sill largely communism, we have seen and explosion in economic growth, which will soon surpass that of the United States economy and Europe Union.