Its not always the older boxes and the amprage. ( i have had my share of reverse wireing, and surges also) Go to disney when its 100 degrees, everyone has the acs on, more draw. I had low voltage there, and thats a top of the line campground. Sometimes the supply to the campgrounds just can not keep up. But yea, I here you about the older used boxes. Unfortunately, we all have acs, tvs, cooking gagets, ice makes, fridges, phones, pads, awning lights, heaters, water heaters, etc. Lots of stuff to be plugged in that people never had in the past. I for one use the voltage instead of the propane as its easier. People like convince. Plus you wouldn't even know unless you had a ems system. Most people dont.
On another note , at a state campground a tesla owner rented a spot in a campground to charge for the day across from me.