I'm not sure I agree with the above post.......
First, I have yet to see a campground 30A circuit with a GFCI but I have not been camping for 20 year so I will assume you might find one once in a blue moon.
But as a matter of fact, if you purchase an adapter like this one that is used to take a camp 30A receptacle and a 15/20A receptacle so you can have 45/50A for a coach with 50A service they explicitly tell you it will
NOT work if plugged into a GFCI. Most camp service that does offer a 15A/20A receptacle on the panel it is a GFCI receptacle and it will trip it every time.
https://www.camperid.com/camco/power...oaAtj1EALw_wcB