Tree maintenance labor, harvest labor, storage before shipping, labor to load the truck, labor to unload the truck, supermarket storage, supermarket shelf-stocking labor, supermarket disposal labor and cost for any stock that spoils.
That's for peaches intended to eat whole. The peaches we're talking about here are intended for canning, so you also have to add the cost of running the processing and canning machinery, the cost of the cans themselves, and the cost of labor to run and coordinate all that.
Also consider that no single supermarket is going to buy out the entire truck, so you're going to be stopping at many supermarkets, and unloading multiple times.
For larger chain supermarkets they may be buying a full truck (or multiple), but then you'll probably be delivering to a distribution center, where the supermarket then has to pay for that storage, plus labor to re-load onto other trucks, ship to the supermarkets themselves, and unload again.
Your analysis is missing nearly everything. Driving the full truck from point A to point B is a tiny part of the process, cost-wise. And I'm sure I've left things out too.
The fruit needs to be picked. Paying people to pick it costs money.
As far as I know, you can’t just load 44 tons of peaches into a grain hopper trailer. It has to be loaded into crates, which are stacked and palletized and loaded into a refrigerated trailer. Possibly this is automated, but I’d bet it’s done by humans.
Food is generally not delivered from a farm directly to a grocery store, (ignore local co-ops buying from local farms for the purpose of this discussion, we have 44 tons of peaches inside our 53 foot trailer) fruit is stored in a refrigerated warehouse and it costs money to store it there whether you own the warehouse or pay someone else to store it in their warehouse.
A grocery chain will have (or rent/rent space in) warehouses where they receive large orders and then distribute them to individual stores, or they buy it from a local distributor that sells to multiple chains. Include unloading from the truck to the warehouse, which is faster than loading the fruit onto pallets, and picking the order in the warehouse to then be loaded onto another truck to be delivered.
Then, someone at the store has to receive the order, and then someone is assigned to stock the fruit on the sales floor, which occupies space inside the store which costs money.
All of your freight costs go up if you ship less than a full trailer (LTL).
You gave the LLM the wrong prompt. You probably asked something like “How much does it cost to ship 1000 kg on a semi-truck in the United States?” when you should’ve asked something like “Name all of the input costs for selling peaches, include all costs starting at harvest and ending at the customer purchasing the produce at the grocery store.”
This is exactly why we have freight brokers.
People seem to think that farmers can't or won't own their own trucks and trailers. Almost everyone I know does.