Its really not feasible. I have asked about aspartame and two of them had to contact their flavor suppliers first to find out if what they used contained it. Most of them buy their flavors from the biggest flavor vendors and those sites don't even tell you what's in them. Then there's the signature juices. Do you really think they're going to tell what's in it and have other vendors steal their recipes? If you have a tank you're afraid will crack, use "contact us" and ask if the ingredients will crack it but they may not know that even. For instance, I have a Banana Nut Bread juice that is found all over the place because so many flavor vendors make it. I had no idea, until watering it down to the point where there was barely any flavor at all, before I could taste cinammon in it. That will crack a tank and, in my case, was making my tongue sore and producing clear phlegm in my bronchials. Its just impossible to label ALL the ingredients unless you made those flavors yourself and most vendors don't....
oh... unless they go to what many food manufacturers have done: "May contain" and a list 10 or more ingredients that would be too much for little juice bottles. And still... who knows what's in it? The best you can do is shop where the vendor seems health conscious about ingredients... they usually put that on the home page or faqs. I shop where they specifically say "contains no...., ....., .... or asparatame." There are lots of them and they're really helpful with "contact us" questions.
Final thought... lets not strap them with too many picky things that can be asked and answered individually because it will drive their and our costs up as has happened with other heavy government regulations. Health... yes... on the major stuff like diactyl but individual allergies... please... no.