I think the number one thing PSFC does to minimize waste is maintain incredible velocity of sales — much of the “free” member labor is used to constantly replenish shelves by cycling goods off trucks, through the basement, back up the belt and out onto the floor. Incredible sales per sq foot and they are ruthless about cutting items that don’t sell. Of course it helps to be in a densely populated area with a large number of members.
Anyway not much rots or spoils on those shelves. Although I sometimes see fruit going bad when shopping but I’m sure the ratio is much better than even most nyc groceries.
I will say given the tight space they tend to buy more packaged produce and potential bulk items than certain other stores in more spacious places (I’m thinking of Monterey Market and Berkeley Bowl in Berkeley where items like strawberries and cherries were almost always in big bins because they bought direct from farmers - psfc probably couldn’t do that due to space constraints and the time it takes for shoppers to bag that stuff).