In some private parks where a large percentage of campers are seasonal it is absolutely necessary to charge a fee for visitors. Otherwise some, not all, seasonal campers consider their RV and campsite as their cottage and like to have friends and family drop by for a visit or a swim in the pool. You can imagine the kind of problems this would create, not only for campground management but also other campers who have paid to use these same facilities. Not to even mention where does everyone park when visiting.