The ADA as written does not address the issues stemming from the fact that certain ingredients are concealed in food and it does not address the issue stemming from the prevalence of cross-contamination.
They have recognized that food allergies can constitute a disability, in some instances this can require accommodation, there are FDA requirements to list major food allergens and contamination possibilities, but that is not a solution for all situations, since lots of people have less common allergies.
I'd be interested in any new or different information, I stand on my previously stated opinion that it shouldn't require a law (even though it often does) to do what is reasonable.