Let's try a voluntary paradigm shift. Instead of assuming that the food we buy is safe, let's assume it is not 100% safe. In other words there is no certainty. [This is my old stat tutor persona coming to the fore, by the way.] Now, since we cannot say something is 100% - i.e. not certain - we can assign a probability value to the issue of food safety. Then it is a short leap to the idea of managing food safety risk. For example, if you grow your own food, you cannot be 100% certain that your food is safe. For example, your dog may be out in the garden chasing rabbits at night and then leave a little deposit on your salad greens. In the morning you may munch these same salad greens without even thinking about it. Admittedly, this kind of scenario has a low probability, say 1%, but I am sure you follow my line of reasoning.
Okay, if we are assigning probabilities, we don't even have to measure them; all we have to do is be in the ballpark or even just rank them. For example, if you grow your own vegetables, you have a greater probability of safety than if you buy them at the store or a farmers market. You even have a greater probability than if you buy from a certified organic grower. (Remember - the E. coli outbreak in 2006 was spread by certified organic spinach.) So now we are actively managing our risk by growing our own produce - even though it is not 100% safe. We can rank them in the following scale.
1) Grow your own - Best
2) Buy from a grower you trust - Better
3) Buy certified organic - Usually okay
4) Buy from a supermarket you trust - Usually okay
Notice how I rank certified organic in the same category as from a supermarket you trust. The third-party certification people will surely object to this assumption on my part, but I back it up with experiential evidence. I look at the nature of the corporation that sells food and this is a proxy for knowing the origin of the food. In other words, I would rather buy from a supermarket that is honest than from a crooked organically-certified grower. Business ethics are the operative deciding point in this case. Notice also that I don't use the category "farmers market." A farmers market is just a venue, not a supplier per se.
The bottom line is to reject certainty as a chimera. Then we can focus on managing risk. Effectively managing risk means making decisions about what we buy. The more active we are the better.