About 99.99% of the time the rules are there to be exercised at the discretion of the Ranger or Camp Host in the event there is some other problem, like excessive noise. It's an easier way for them to get unruly parties to move on. The only park I've ever stayed at where one rules was religiously enforced was at Guadalupe Mountains National Park. They have a rule of no RVs in the tent camping area and no tents in the RV (parking lot) camping area. I saw them run off a couple on a motorcycle who set up their tent in the RV area because "the tent was not attached to the motorcycle and was therefor not an RV". But they did direct them down the road a few miles to an area on BLM land where they could stay for free.
