I do not believe it is required for most places and so far the last few months theres been no observed electrical problems anywhere I've been.
However now that i have something that will give me an accurate voltage at the plug in source i can test some places I've been when i go back.
The under voltage is the reason i got it. Most state parks and decent camping areas dont have big electrical problems that otherwise would be detected by this that you couldn't get a lot cheaper with a meter or camco plug in device.
The point of this device is thr automatic shutoff and reconnect for low or high voltage when a camping area is busy.
I'll definitely update this later as it's put in use
ETA: Fried one of the hot wire sides after just under three years of use. I'm not sure if that is good or bad but expensive every three years if this is the trend. It does still work though. But when I went to disconnect from the house while it was stored for 5 months under my carport with the AC set at 85F, one black wire plug was burnt. I had to buy a new RV cable too just in case it damaged that too. So I had to spend another 300 dollars on a new version, 34930, and a new RV power cord.
Hope the new version lasts longer than three years!