No, this is where traders come in.
Yes, you can write 20 buy orders for 100 bushels each. But you can also write out 4 orders for 500 bushels each, and wait for a trader to do the work of getting you the batches.
Or you can write one or two big ones for traders and a few small ones for the other region lords to accept immediately.
Plus, of course, your region lords can put up sales orders in the magnitude they can afford and you can buy those.
Really, why is everyone so focussed on the "this will be horrible" part? Right now, it seems that for every change I make, I need to go away for a week afterwards until the complaints have died down and everyone has realized that the world is still turning.
This would require region lords to post sale orders, which friendly people in other realms can buy instantly. So that brings back the original problem of not being able to protect your food. And the solution that was offered for that was to put up manual buy orders. But a trader for example still needs a sell order in a region to match large buy orders. All I ask for is a way to prevent other realms from buying food with it not requiring a lot of time of the person buying the food.
Artemesia, thank you for your wonderful comment. Go manage food yourself and then start crying.
