Unless they get hit in the wallet,as you indicated, nothing will change.
But that's almost impossible, even if the public knew. Most companies are conglomerate and thus unless you know every product under every name, you can still be buying from nestle without knowing about it. ADM is one just like that, or Coke and Odewalla bars. Most people would not be able to boycott most fodd companies because it's almost impossible to know what other products under what names.