Another reason for qualified persons doing electrical work, most of us wouldn't bother to look at the diagram but a DIY home owner or park maintenance person might follow the instructions to the T and end up with reverse polarity on the 20 amp by doing so on this RV pedestal.
Would a new GFCI even operate with the wires reversed? I thought they had polarity protection.
BTW just poking around looking for a 5.15 picture I saw this. https://www.americord.com/wp/wp-content/uploads/2022/03/AYzATpJ5SjLtB5.png
Good point, a new GFCI won't work if line and load are reversed but I am not sure about polarity protection, I haven't heard that before and don't see any reference to it anywhere except that RVs built after a certain date are supposed to include reverse polarity detection at the RV itself.