Computer scientists had this idea that some things should be public and some things private. Java takes this to the nth degree with it's public and private typing keywords. R just forces you to know the lib:::priv_fun versus lib::pub_fun trick. At best it's a signal for package end users to tell which functions they can rely on to have stable interfaces and which they can't. Unfortunately, with R's heavy use of generics it gets confusing for unwary users how developers work with the feature as some methods (e.g. different ways to summarize various kinds of standard data sets as you get with the summary generic or even the print generic) get exported and some don't with seemingly no rhyme or reason.

Don't worry they're just a bot. R doesn't hide functions.