I’ll quickly try: there are a handful of big supermarket chains - the article and the video reportage mention Coop, Conad, Gruppo Selex, Esselunga, Eurospin - that set prices and mandatory discounts. They essentially don’t compete, and fairness is only left to goodwill (e.g. Coop is historically tied to the Left and operates under a more worker-friendly CoC. In theory.)
Access to consumer markets is either via a looooong chain of small, inefficient and parasitic intermediaries or via the GDO, the logistics organizations of these few supermarket chains.
So the farmers are squeezed, they fall in debt and go bankrupt, or sell out to big landlords; and both tend to employ illegal immigrants under inhuman working conditions to meet the prices set by the aforementioned.