The difference is when the US government does something nasty, it's relatively transparent and accountable. It is not the case for the China government.
From where I'm sitting, both are not transparent and accountable.
Both Chinese and Americans can protest about the US government's scandals on an internet forum hosted on the US, not the other way around though.
Do you actually have any firsthand experience with Chinese internet culture? There's plenty of discontent and protestation about government policy, it's everywhere.
... in other words, information about the nastiness is leaked