Two night stay requirement

Many campgrounds have the 2 night minimum on weekends and/or during their peak season, especially at preferred locations. The reality is that a 1-night stay is actually less than 1 day. With a 2pm check-in time Saturday and a 10am checkout time Sunday, that gives you just 20 hours. 8 hours of sleep right in the middle leaves just 12 hours (6 & 6) to setup camp, enjoy, and tear down camp. Not worth the trip for many, especially if they are traveling very far. Paying for that extra night (Fri), even if you don't come in Friday night, allows you to come in early on Saturday morning, giving you the entire day to camp/relax.

As for an overnight while traveling long distances; there are many options for a quick overnight stay without "camping", particularly if during the week.