The Hosts are, first and foremost, wineries/farms/museums and do not provide the services that you would find at a campground.
Locations with hook-ups are the exception rather than the norm, and for this reason, we require all members to be self-contained. We understand that in hot weather it would be nice to have electricity, and the Hosts are amenable to allowing reasonable use of generators during a visit. You just need to ask when you call for a reservation.
You will notice that some of the Hosts will mention on their page that hook-ups are available. Some provide this complimentary (usually electric) and others have an optional (but not required to use) hook-up available for a charge.