In the docs it says you can pass
private_info for scope when authenticating a user.
What does this allow you to access, that you couldn't otherwise?
The documentation says about
access full history of a user's private actions on the site.
What this means right now (API 2.1) is that that scope is needed to use the
Returns a user's full reputation history, including private events.
This method requires an access_token, with a scope containing "private_info".
This method returns a list of reputation_history.
According to the docs, at least, no other paths require that scope.