At the campground supply panel there is a connection between the neutral and ground. Between the campground supply panel and the end user the neutral and ground wires are to be maintained as separate circuits (pedestal, rv). The typical rv has only single pole breakers (you can check this yourself) so only has 110v service available. If you have a double pole breaker then there is something using 220v in your rv. I expect now that 220v is available at most rv parks, 220v equipment will be transitioning into the rv industry.