Hot showers too! And 1-800 phone numbers. In my motorcycle touring days, at 3pm or so I'd figure out where I would be at 7-8pm, lookup the nearest KOA in the KOA directory booklet, and call the 1-800 to make a reservation. Often when I arrived, they were turning away unhappy would-be campers as all spots were already taken.
I've been turned away a few times. Real campers (not people on an 800lb hog or hauling a 3 ton tiny home doing 7mpg) are using a tiny fraction of the total area and all that space is wasted. they could be making more per camper per night by splitting camper sites by making small footprint spots where they otherwise couldn't put a car site. This is what a real campground spelled with a C does.
These days the trick when motocamping in the east is to look up the KOA location, and then check the rate at the local campsite across the street or down the road.
Out west of course you usually have free options.