I would be very concerned about someone charging my card without telling me beforehand. We have never had to give our credit card info to the employee at the booth when the site was already paid for. If there was a vehicle charge we were told and then had the choice to pay cash, check, debit or whatever. The reservation company's do not do any of the additional fees, however some parks do include at least 1, sometimes 2 vehicles per site with the camping fee. They can tell you if any were included without additional payment and the parks website should tell you about these fees if you want to check on it.
