While a campground's initial installation may be up to code to pass the inspection, there are, to the best of my knowledge, no "annual inspections" to make sure they stay that way (my father and I owned a bowling center eons ago and we had no "annual inspections). There is no telling when or who has worked on those circuits since their original installation and no telling what "unreported" changes have been made since that time. Just because they met code at one time, doesn't mean they are still up to "code"; a code that is continuously evolving.
The better devices (not the $100 ones) will also protect you from nearby lightning strikes (externally induced surges), sagging voltage and mis-wired (handyman repairs) pedestals. Sagging voltage, IMHO, is more dangerous to your equipment and more likely to happen than the other problems.
Most campgrounds were built in the era when few rigs actually drew any where near 30 amps. Now, most rigs are right at their 30 amp drawing capability (or over, depending on what appliances they've added - check the forums for folks asking why they can't run their crock pot along with the hair dryer and the A/C
). During the high heat of summer, a fully loaded campground's voltage can be taxed to the point of a severe "brown out"...voltages of less than 108-109 can damage computer circuitry, A/C compressors and other digital devices. The better surge protection devices will actually shut off the electricity when those low voltage events happen, before damage can occur.
Now for real life experiences. I towed a FunFinder 210WBS for a number of years and now tow a Cougar 5th. Along with the built-in electronic devices, I also carried computers, upgraded television and DVD hardware and other miscellaneous digital pieces of electronic hardware. My SurgeGuard has cut the power to my trailers 5 times over the years. All the instances were during high heat stays in the desert southwest and once in Idaho. Would I have been OK without the SurgeGuard? Who knows. The cut off periods weren't long (I think the longest was around 10 minutes) and I didn't mind the loss of electricity...a minor inconvenience compared to maybe replacing my microwave or a new compressor for the A/C or some other damage. Another instance was during a thunderstorm in Nebraska. The power went out in our area of the park after a nearby strike (scared the heck out of the cats!)... I still don't know if it was the SurgeGuard that protected us or luck of the draw, but, the guy next door was calling around the next day trying to locate a new controller board for his refrigerator...we were fine when the power came back on.
Do you need one? Probably not. Many, many folks out there don't use one, haven't ever used one in the 300 years they've been camping and don't ever plan on getting one and they do just fine. Then again, you could be the guy trying to find a Dino board for your refrigerator on a Saturday night and trying to figure out where to get enough coolers and ice to get you by until the repair can be made...
I've had one (30 amp and now a 50 amp version) for my rigs. Compare the cost of one to the cost of repair to your electronics along with the downtime and then what you want to "gamble" on the odds. I've never been much of a gambler when the protection is so relatively cheap (cheap and RVing don't go together, no more so than boats, I know, I've been that route, too
) I'm retired IT and know about surges, sags and brown outs and what can happen to delicate equipment. All of my equipment in the sticks and bricks is also protected in a like manner and some are even connected to UPS (Uninterruptible Power Supplies) for further protection...why wouldn't I make the same investment to protect the devices in my RV?
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