I was browsing the map and the link that is in the pop-up box for Tres Hermans Winery in Los Olivos, CA was not working right. It just opened to a new copy of the map in a new tab.
That clearly is a defective listing, but, nonetheless, it appears that the small campground there is only open to members of the winery's monthly bottle club. That would normally not be considered an RV park suitable for listing in RVPR since it is really just customer parking. So I would not expect this listing to be corrected; most likely it will be removed.