maybe they should let us put food in the stash that the garrison would eat from and that merchants like caravans would not be able to take and sell to other places because i feel part of the problem is when i sell 500 grain to my city to save it from starving then the caravans buy it all because its so cheap.
There's plenty of things they could do to help this issue.
Caravans :
You're right about caravans hoarding the food, caravans should trade mostly other goods than food, and just take in food what they need to sustain the caravan guards. It shouldn't be a way to balance the food needs of the different towns. If the devs want to balance food, make it so food can be traded in limited amount, not by every caravan ever.
Securing supply and trade routes :
They need to reintroduce bounty hunters and patrols to chase bandits and looters and stop them from disturbing villagers and caravans constantly. Maybe not too much, there still need to be some disturbance, but just bring back the bounty hunters and patrols in the future.
Make kings and lords chill the hell out :
We get it, Mount & Blade is a war game, but not just that, nobility should do something else than to just pack up in an army and walk around even when at peace, they syphon a lot of food in the areas they're in, that doesn't help at all.
Create reserves made to sustain armies exclusively :
Maybe there's a way to create some sort of warehouse in towns and castles that stocks a portion of the available food on the market based on the needs of the garrisons and the lord's army who owns the settlement, but that's hard to do if there is no food left because the caravans pick everything.
But I recognize it's all a lot of work and I'm patient. I'm just making suggestions, not being an ass and complaining about it.