Not sure anyone is spending time and money on this labeling thing. You produce GMO free food, label it as such and whoever is into GMO free can assume all the rest contain GMO and not buy them. Everybody can move on.
Then again, that won't be good enough either. Apparently Chipotle calls its meat products GMO free, but some enterprising lawyer, ready to cash in is suing them, cuz the food that the animals eat is not GMO free. So there you go....
Anyway, most of the food we eat today is not what is was 100 years ago. Thru careful selection and breeding they ere modified. Genetics does the same thing except it does not take generations to do it.
You can carefully breed and apple that does not turn brown in several generations of apple trees, or you can get a good engineer to do it in a few years.