I imagine it is easier politically to shut down a small dairy farmer, but I imagine it's also a lot easier to grow e-coli in a dairy that does not use pastuerization compared to a grower that does use a washing phase.
Other than cold temperatures, there isn't any treatment of the milk to remove harmful organisms. They could reside anywhere, but especially holding tanks were they to be infected. The produce gets washed which reduces the possibility of contamination before shipping. Also, don't these growers and processing plants ship more than just spinich? I imagine they process other greens that weren't contaminated in the way the spinich was, so a complete shutdown would likely be just as politically motivated.
It makes sense to scrutinize the dairy farm more since its production could result in a huge bacteria soup compared to the produce farms.
Your logic makes sense, but the reality of production is somewhat counter-intuitive. As I understand it, part of the spinach problem, what California Department of Health Services officials refer to as "systemic problems," is that large amounts of spinach are washed together in huge vats, allowing bacteria from just a few leaves to spread around. The raw milk dairy has built in safeguards against e.Coli-type problems, such as feeding cows grass rather than grains (reducing likelihood of certain diseases in cows that could be passed on to humans), and following strict cleanliness standards in the milking process, where contamination could also occur. There are all kinds of good bacteria in raw milk, which it's healthy to ingest, and which get killed off in pasteurization. After hundreds and hundreds of tests at the Organic Pastures Dairy, no pathogens, or bad bacteria, were discovered, in holding tanks, barns, or even in the cow manure.
What I'm suggesting is that the spinach growers might be more motivated to eliminate the systemic problems if they knew they'd be shut down. Thanks.