Maybe the example has been weak. I didn't mean "trust". Trust nobody ;-) !
I meant that - in our economic system - you can elect by buying something that even might only be a placeholder or symbol what you really want.
My point of view is that I even though I might distrust the supermarket buy an organic tomato to tell them that I want farmers to grow organic tomatoes and that I want them to sell those tomatoes.
I distrust the supermarket, but for my goal it seems irrelevant to me.
