They are completely different outlet types though. You can’t plug a NEMA 14-50 pluck into a TT-30. Apps such as PlugShare will indicate if it’s NEMA 14-50. Hopefully the Rivian head unit will as wellCamp grounds are pretty good to charge at... but FYI the 30 amp outlet is 120 volt. The 50 amp in a campground is a Nema 15/40 which is 240. (Mainly used on big coaches and 5th wheels)... 30 amp plug in campgrounds is a TT-30 receptacle which is a 120 volt outlet for smaller travel trailers.
just don’t want people to be disappointed in a campground and plug into a 30 amp receptacle and not charge at the rate they are expecting.