It probably has more to do with education and progress. The more education and progress there is the less corruption. But little or minimal corruption does not mean open society either. You can have an autocratic system with low corruption.
Do you think a ruling class can be educated into not pursuing their personal gain at everyone else's expense?
It's not that complicated. 2 + 2 = 4, and "fucking people over is bad mm'kay?"
The problem is that opportunities for "corruption", wealth and power are the main reasons why psychopaths seek political office to begin with. They don't go there to help others.
A more educated population tends to demand more reason.
Not when it's "educated" by the government itself.
The public education system is a brainwashing program, to make us unquestioningly obedient to authority, and to think we need more government intervention in everything.