If I go to Tampa to visit Busch Gardens, I want to spend the night near Busch Gardens, not at some hour away campground. If WalMart is OK with me spending the night in their parking lot, what's it to you? I'm totally self contained and quiet besides.
If I'm driving cross country, then why on earth would I pay big bucks for the amenities of an RV park just to sleep? Those places aren't cheap. All I need is a place to get off the highway and catch 8 hours of sleep, then I'm up and on my way again. Not at all interested in hooking up to water, electric, etc., just in turning off the engine and taking a snooze.