I'd like to know that too. Adding a couple of words to a label costs nothing. Perhaps they're worried about the extra ink?
There might the be added cost of verifying the information. Still, I say "Label it and let the consumer decide".
Some years ago there was a flap over whether or not dairy companies should label milk cartons as to whether or not their cows were given RbSt (a growth hormone that increased milk production). The dairy lobby said no labels, the FDA supported that saying that it was not considered an additive to the final product. How stupid are we? I will make the decisions about what edibles enter my house, thank you very much.
again: Label it and let the consumer decide!
Seems consistent with free market philosophy to me.