score:6
Most commercial campgrounds have office hours and tend not to be open real late, say 8 or 9pm.
But if you have a reservation and haven't checked in by closing time, they will put a note on the office door telling you which campsite is yours and requesting you to come check in after they open in the morning.
A fair number of campgrounds will allow you to simply choose a campsite, if you arrive without a booking after hours, and then come pay in the morning. The drawback however is you may not have the passcode to enter the restrooms or showers.