It should be a requirement even though its not. Most people just chalk most of their Air Conditioning, TV, Transfer Switch, Etc failures in their RV's to cheap equipment installed by the manufacturers however most times its bad campground wiring and extended brownouts from the local utility companies that are causing these problems.
I had a Hard Wired Surge Protector with automatic shutdown for low/high voltage along with all the common wiring issues yet was too regularly dealing with failed start capacitors, burned out motors, overheated circuit boards, etc, etc until I put in a voltage correction transformer. When there was an extreme low voltage situation where moving to another campsite or campground was not an option during a low voltage shutdown on your surge protector you could be left in 100+ degree heat having to decide on hitting the bypass and taking your losses or toughing it out such as in the summer of 2008 where most of the East Coast was plagued with low voltage during that heatwave event.
The voltage correction transformer takes care of the low voltage situations that even the expensive surge protectors allow to pass, along with most that they would shut down for, greatly extending the life of your Air Conditioning, Microwave, TV, Transfer Switch, so forth and so on. The Hughs Autoformer I installed in my coach had paid for itself in the first year and many times over on the cost of repairs over the past 11 years not to mention the convenience of not having to decide if I wanted to hit the bypass taking my chances or go without power. Now I am just looking at an indicator telling me when the voltage coming is is damagingly low however the Autoformer is automatically correcting it.
You have to decide if its better to be replacing equipment more often, putting in a surge protector and having power shut off on you when there is a brown out or having a system that fixes voltage issues for you without shutting down your entire coach until the power incident is over.
I travel with a dog and its much nicer to come back to an air conditioned coach instead of a hot one on low voltage shutdown with an overheated dog inside.
2001 Winnebago Adventurer WFG35U