> Yet strangely, before mass-market supermarkets existed, people in rural areas ate fresh produce directly from farmers

Before mass-market supermarkets existed, rural people ate fresh produce often only because they grew it themselves, not because they were able to buy it direct from a farmer. To buy from a farmer, you need cash, and a lot of rural families were cash-poor. Instead, people in the countryside maintained their own gardens and they made a lot of pickled foods for the winter. However, that is all a lot of work, and in fact historically a lot of rural families had poor nutrition in terms of fresh vegetables in spite of living in the regions that these vegetables came from.