To be fair, here's the complete paragraph which makes sense:
Vagrant public networks are less private than private networks, and the exact meaning actually varies from provider to provider, hence the ambiguous definition. The idea is that while private networks should never allow the general public access to your machine, public networks can.
I've never got network classifications around the wrong way but this is exactly the kind of overthinking I get all the time...
Turn it to the right? - Ok am I unscrewing or screwing here (From the perspective of the top or the bottom?)