I get what you are saying, but I don't see anyone making that assumption. The whole lesson of the English ( vs French ) Enlightenment was that we are *not* good and therefore have to structure society in a way to protect people from an oppressive state or the assumption of unlimited power by the most venal.
It is the very reason so many in this country are suspicious of highly centralized government power and intrusion into the everyday lives of citizens. It is true individuals can and will commit crimes - but governments can commit atrocities.
Charles Hankey
Though a good deal is too strange to be believed, nothing is too strange to have happened. - Thomas Hardy
Half the harm that is done in this world is due to people who want to feel important. They don't mean to do harm-- but the harm does not interest them. Or they do not see it, or they justify it because they are absorbed in the endless struggle to think well of themselves.
-- T. S. Eliot Democracy is two wolves and a sheep voting on what to have for lunch. Liberty is a well-armed sheep contesting the vote. - Ben Franklin
Pardon him, Theodotus. He is a barbarian, and thinks that the customs of his tribe and island are the laws of nature.