The entire essence of my original post is: a simple, established, standardized labeling system wouldn't require one to pore over the ingredients of a food, or contact the manufacturer for more information.
Even the listing of the ingredients is not enough, for those of us who take this matter seriously.
For example, does the product has cheese? If so, does it have animal-based rennet? That fact is rarely listed; you will need to contact the manufacturer.
Observant Jews have established a standard for what is marked as kosher. You will see this mark (a "U" with a circle around it) on many items in a grocery store. I also understand that there are separate marks for what is kosher and what is kosher for Passover.
There are far, far many more vegetarians/lacto-vegetarians/ovo-vegetarians/ovo-lacto-vegetarians in the world than there are observant Jews. So why cannot there be a simple standard for us?
And the vegetarian mark would be easier for the manufacturers than the kosher mark: the vegetarian mark would just certify the ingredients; the kosher mark not only certifies the ingredients, but also that a rabbi blesses the food, and so on.
Am I being unreasonable in asking for a standardized mark?