Visitors search from nearby. Somebody staying in the region types winery tours with a date in mind, so opening hours, booking and how long a visit takes decide which estate they choose that morning.
Experiences are bought as presents. Tastings and tours sold as gifts are searched hard before Christmas and birthdays. Leave the voucher page up in February and it will still be there when December arrives, which is the whole trick.
Buying direct is a deliberate act. Somebody searching to order from the producer has decided to skip the supermarket, and they buy in cases rather than bottles and come back annually.
Grape and style bring the knowledgeable. A particular variety, an ageing style or a specific appellation comes from somebody who knows what they enjoy, and those visitors become club members rather than one-off buyers.