These ridiculous policies are put in place as scare tactics to keep people from destroying the campgrounds property. It makes people think the campground can arbitrarily charge their card if they tear something up. Think about it for just a minute. If I see a charge on my card for anything other than the price I agreed to pay for the site, I'm calling my card company and telling them I did not authorize that charge. And they will reverse it.
So basically all the policy does is penalize a family that does not have a credit card.