Ground leases for residential properties are a very unsual. There are no 'standard' MLS categories to reflect that condition of ownership, hence, the lots "for sale." Technically, was is owned are the IMPROVEMENTS on the lot. In practice, the RENEWABLE 99-year leases, (whose right to renew can be passed along), allow the homeowner to 'control' that lot, just as a restaurant would control a highway side pad with a 20 year ground lease.
Although the Camp Meeting Association 'owns' the land, you can bet Neptune Township will be happily collecting your property taxes. As I said, it's an unusual situation that's a holdover from the 19th century. It shouldn't effect your love of the town and any decision about home ownership there.
Keith Radhuber (former Grove owner, and current lister)