Geography plays a huge role. Riombara isn't close to any food buyers, so lords don't have anything else to do with their food either. A completely different example would be the lords of western Dwilight: if their own dukes won't pay them for their food, then they know (or should know) that D'Hara *will*, and at a considerable price. D'Hara is therefore making a pressure on all western food markets, driving food prices up regardless of where it is sent. I can't say to what extent this is actually going on right now, though, but I suspect it will only increase. After all, D'Hara mostly deals with regions directly, and not realms, as rurals often feel a lack of love from higher up.
In D'Hara, rurals and townslands are also paid the maximum allowed amount for their food. While this does indeed redistribute food to where the majority of nobles now currently resides, the main objective was to incite profit-seeking lords to maximize their food outputs for their own sakes, therefore helping the cities out.
For this, though, D'Hara is unique, and I'm becoming more and more interested by how food is actively transforming the realm and activities around it.
Reading your numerous forum posts about D'Hara and its amazing trade I always wondered how much are you really able to gather. Almost every realm on dwilight struggles for food: very few have surplus and since food it's an insanely powerful strategic asset, food market is strictly controlled in several of those realms. I would bet that all lords or traders caught selling food where they are not supposed to get a free ticket for a ban almost in every realm of dwilight. Certainly you can have a few traders on your paybook that run around and steal food or perhaps some lord that sells to you without being noticed, but these would make such tiny quantities as to be completely irrelevant on the large scale. Also, not so many lords are playing the selfish greedy guy, I guess there are quite a few that would gladly sell food cheaply to their own duke without thinking twice.
