If you are a senior in Florida - Half price. SO, if a senior reserves a site, and then No Shows, it cost more to cancel than to ignore it.
There is a little variation in park fees - but generally $16-18 x half. So, a cancel of $17.50 is a wash, more or less. That's why people simply don't show up, because the PARK gets the camp fee, and RA gets the cancel fee.
Altho, we most often do not reserve and just show up on a day we want to camp, if I were to reserve, and then cancel, I'd ignore the cancel and let the park keep the fees. We almost always get a walk-on site, unless a holiday weekend.
I know, makes little sense - but it's just the math of it, not the ethics. But on those few occasions we reserve and then are unable to go, we call the park and just tell the rangers to give it to a walk on.
Of course, it makes more sense to cancel if the stay is longer than a weekend.