I see. But food transactions are not invisible: bankers are informed when someone buys or sell food, dukes and rulers get food movement report and with a bit of math they can easily find out if a couple hundred bushels vanished. Clearly that holds only if they have some realm wide food policy and if they care. I suspected more realms had but it appears is not so.
As for the communistic approach, it's not about SMA or not, it's just about being reasonable. If Lords starve their own cities, this easily means they will sooner or later have no one defending it from monsters, as certainly one rural can't field by itself much of an army even with good trade deals. Plus usually judges are more tied with dukes than not, so it's really not hard to put lords in line if one wants to. For sure there are enough holes in the net for people to smuggle as much as they want, but I am surprised to discover it's not the exception.
Bankers only get note of huge transactions, if even that I believe. I don't quite recall, I haven't been a banker in a while. I could ask my banker to clear this up for me.
The communistic approach is not reasonable, that's the whole point. Cities produce a ton of gold, and rurals very little. If their cities are unwilling to share their wealth a bit, then why should the rurals? None of my transactions are in tiny realms with food problems, there is always the gold there for it. And even when the realm is more conservative, it doesn't mean that their cities are starving either. It just means they want to be prudent at their rurals' expense.
Many rural lords would be willing to make a bit less gold by selling internally, I believe, so it's just for the local duke to offer a reasonable deal (and not necessarily as high as ours) and they will deal with them.
Finding food leaks is also not very easy.
