It's not perfectly balanced, but then again, it doesn't need to be. And rural lords will most of the time be at a disadvantage, since even if they are crazy or ballsy enough to sit on their food while cities starve, they'll get scolded and/or punished for it.
Removing all tax income from rurals would shaft the lords to no extent in most realms. To give you an example, my region on BT is the third biggest food producer in Riombara, with a daily net of 31 bushels per day, so 217 bushels per week. Riombara produces a surplus of food, so prices aren't terribly high. If I was forced to sell my food at 30g per 100 I'd get a total income of... drum roll please... 65 gold per week. And I'd have to sell ALL my excess food. At those prices are higher than what they are right now.
