While they could have been accommodating, they are well within their right to act as they did. Whether it’s Adventureland, Disney World or Great Adventures, theme parks are universally expensive and universally (as far as I know) require that all those entering pay admissions. Some parks also charge for parking.
If this is too much of a financial burden, there are a number of beautiful alternative activities that are free including many NYS parks with stunning hikes, picnic areas and the like.