HortNZ advises that they've had some success with their repeated request for independent fruit and vegetable retailers to be permitted to be open under levels 3 and 4.
With reference to the section on Workplaces, Alert Level 3, the inclusion of greengrocer will allow fruit and vegetable retailers to remain open.
The Covid-18 website here states:
[At Alert Level 3]: 'Businesses cannot offer services that involve close personal contact, unless a supermarket, dairy, primary produce retailer (eg greengrocer, fish monger or butcher), pharmacy, petrol station or hardware store providing goods to trade customers, or it is an emergency or critical situation.'