There is NFPA 1194 "Standard for Recreational Vehicle Parks and Campgrounds". It covers site layouts, sewer requirements, potable water requirements, pedestal locations, etc. An older free version is
here. I don't know if this standard has to be adopted at a state level or by a local authority having jurisdiction.
Even if there is a standard, many CGs go back to the 50s & 60s when there weren't any.
Trees? :E Have been to a few on the west coast where it's literally like a jungle and on leased native land where cutting and pruning of trees is prohibited. Very hard to get around corners and into sites. If you look up at overhanging trees & limbs you can see where they've been whacked more than a few times.
Then there was the CG near Wenatchee WA we were just at. Very few trees anywhere and around 105F temp. OMG, we thought we were gonna die even with the AC running flat out.