Reservations

I still remember years back when most RV parks accepted reservations on the honor system. You just called and told them when you were arriving and how long you would be staying and they wrote it down in a book. Then over the years as parks got busier, folks started multiple booking sites at more than one park "just in case", and didn't bother to cancel the ones they wouldn't be using, costing the park lost revenue while sites sat empty. Hotels used to reserve on the honor system as well and eventually realized they were losing revenue also while rooms sat empty. And the current deposit required reservation systems were born...