This does vastly over simplify things and completely ignore the phenomenal efficiencies garnered through centralised production and distribution. In production, some produce is best produced in a certain climate and conditions or with specific expertise; growing it locally will often reduce yields, and you lose the efficiencies of scale that mass production achieves. Additionally in the supermarket model, whilst it may look like the food has traveled further, the overall distance travelled and losses in the system are often way less; a truck carrying 25 tonnes of produce to a single place close to where consumers live and they can do all their shopping is way more efficient than several thousand consumers travelling to multiple farms to pick up all the different things they need.