It really depends. In high cost of labor countries, the long supply chain likely is cheaper due to many small compounding reasons.

In low cost of labor countries, I've seen the exact opposite. It's probably not very profitable in the US to setup a vegetable stand for 12 hours a day along a highway for $10/hr of sales. In many countries it is - you have a market garden and put one of the grandparents/children/cousins/etc. manning the retail operation. A single western tourist can make your entire day profitable (including opportunity costs) assuming no other sales.

In my experience you pay a huge premium in the US for locally grown (e.g. weekend farmers markets) - but in other countries it's the opposite - supermarkets are pretty expensive, and the "local farmer" markets are a quarter of the price.

It gets even more crazy, though. Very frequently there are weird market conditions that create massive losses for large suppliers. Random google link: https://www.freshplaza.com/article/9056981/india-tomato-whol... You can see that the price dropped as much as 74% These things happen around the world surprisingly frequently.

Large supermarkets, etc, can get access to these ridiculous prices and so it can cause prices to stay fairly low. However, it is not really healthy for the farmers. If you live in a really rural area that doesn't have access to a large world-wide market, the local food will be a lot cheaper because the only outside food you have access to is super expensive.

For me, buying local is about agricultural sustainability. It's about making sure that my neighbours can grow food, sell it and live comfortably. I'd also rather have many small farmers producing the best quality produce they can, than 1 super farmer that is trying to produce the cheapest produce they can. This all adds up to higher prices, of course.

I often feel that we should have "fair trade" in food everywhere. I can buy a pound of raisons from California for less than $2. The same grapes would be 4 pounds. $2000 of raisons at a retail price is 4000 pounds of grapes... And you think for those tonnes of grapes... how much is the farmer getting? It gets a bit crazy.

Maybe it's cheaper to transport raisins than grapes? They are smaller so you could fit more of them on a truck. Also they are already dried out, so they may be less sensitive to shipping conditions.

It certainly is, but imagine a pile of 1000 pounds of grapes. Imagine an iphone. They have the same retail cost. Is this reasonable?

In Kazakhstan local food is not cheap as well. Yes, human labor is cheap. But that means that it's cheap for supply chain as well. I live in Astana and a lot of fruits are imported from Uzbekistan, even those that could be grown locally like apples. There are people who grow apples, potatoes and other vegetables in their gardens, mainly for themselves but they also sell what they don't need. And that price is not low. On the other side, imported vegetables usually don't have good taste, probably because they are optimized for export, so that high price vegetables have their buyers.

As someone who lives in Africa, I can assure you that the cheapest food around is locally grown. My guess for why is that import duties make a sizable chunk portion of the cost and that the infrastructure for keeping things cold/fresh is expensive or non-existent, driving up the risks and costs of importing fresh items.

In a country with a less developed transportation network local food will be cheaper than transported food. Keep in mind that lowering food prices for a developed country is a much different optimization game than lowering food costs for an undeveloped country. Not every country has a freight rail network as effective as the US.