Food Distribution Troubles

https://preview.redd.it/d8181eun4zhe1.png?width=2111&format=png&auto=webp&s=c2689b145fe7979ef1afd306eb6b4cb4c1b98aaa

As the picture shows, I have way enough food all year long (this is the weaker month, in summer there are berries on top), yet my people are too stupid to buy food/sell food and food variety is a constant 18-20% (which is just the 3 houses which actually buy food. All other houses are constantly red and just dont buy food. I cant upgrade the plots because they constantly complain about food.

I have enough staff attached to both the market and oxen. There are also many free workers. Why cant they just fill the markets??