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.
A transaction of about 200 counts as huge. What I can't remember is if you see these all all for automatic trade offers and the auto caravans.
Also its not exactly a communistic approach. Food from a rural area to the city can be viewed as part of the tithe owing the Duke as part of the oath. It could be argued that an instance on payment for food is capitalistic, neither statement is completely correct.
