The fruits of high value could be sold in low volumes, the gross profit on the item would be high enabling more profits. Example: Cherry, Plum, Kiwi. The same seller will have to specialize in fruits available as per the season. Whether the winter season oranges are available or the Summer season when Blueberries, plums are available.
The item of low value had high volumes to compensate for freight costs & lower profitability. Example: Onion & Potato.
The items of low value could be customer centric and different products in the customer basket could be kept in combination of being jointly consumed. Like in making any dish Ginger & Garlic is jointly consumed, onion & potato or onion & Tomato is jointly consumed. The items mentioned above are generally sold together.
Vegetables and fruit were never sold together. Selling each separately is a sign of specialization wherein the buyer feels the seller has proficiency & knowledge about what they are selling.
The customer psychology for food worked on specialization and not diversity. Since food connotes health. The vegetable/ fruit seller would signal his expertise through the variety of fruits he kept.
A person who kept pineapple, Bananas and mangos only kept this fruit.
The fruit and vegetable seller are a mini Walmart which buys in bulk and sells.
It would keep a certain % of fruits/vegetable as a wastage after keeping his profit in account. The wastage denotes a loss incurred.
An item like curry Leaves in South India, Mirchi in other parts of the country are demanded by customer as free, maybe this connotes as an additional value add which the Indian customer is looking at sweeting the deal.