Approximately zero campgrounds have the capacity to charge more than one EV. They are sized for intermittent loads, just because it uses a 14-50 does not mean it is intended to support 80% steady draw.
Also, a bog standard 14-50 is likely not suited for 80% steady EV usage anyway. They make EV-rated 14-50s now because people keep melting the older ones. And that happens even though the vast majority of chargers won't draw more than 32A on a 14-50 due to the historical popularity of using 40A breakers for a 14-50 receptacle.